HEC-GeoRAS Users Manual

US Army Corps of Engineers Hydrologic Engineering Center

HEC-GeoRAS GIS Tools for Support of HEC-RAS

using ArcGIS®

User's Manual Version 4.2 September 2009 Approved for Public Release. Distribution Unlimited. CPD-83

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7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) US Army Corps of Engineers Institute for Water Resources Hydrologic Engineering Center (HEC) 609 Second Street Davis, CA 95616-4687

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12. DISTRIBUTION / AVAILABILITY STATEMENT Approved for Public Release. Distribution of this document is unlimited. 13. SUPPLEMENTARY NOTES HEC-GeoRAS 4.2 intended use with HEC-RAS Version 4.0 or later. 14. ABSTRACT HEC-GeoRAS is an ArcGIS® extension specifically designed to process geospatial data for use with the Hydrologic Engineering Center’s River Analysis System (HEC-RAS). The tools allow users with limited GIS experience to create an HEC-RAS import file containing geometric attribute data from an existing digital terrain model (DTM) and complementary data sets. Water surface profile results may also be processed to visualize inundation depths and boundaries. HEC-GeoRAS is an extension for ArcGIS® software. ArcGIS® with the 3D Analyst and Spatial Analyst extensions are required to use HEC-GeoRAS. ArcGIS® is a general purpose geographic information system (GIS) software program developed and copyrighted by the Environmental Systems Research Institute, Inc., Redlands, CA. 15. SUBJECT TERMS Hydraulic modeling, geographic information systems (GIS), digital terrain model (DTM), triangulated irregular network (TIN), GRID, HEC-RAS, ArcGIS 16. SECURITY CLASSIFICATION OF: 19a. NAME OF RESPONSIBLE

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Standard Form 298 (Rev. 8/98) Prescribed by ANSI Std. Z39-18

HEC-GeoRAS GIS Tools for Support of HEC-RAS using ArcGIS®

User's Manual

Version 4.2 September 2009 US Army Corps of Engineers Institute for Water Resources Hydrologic Engineering Center 609 Second Street Davis, CA 95616 (530) 756-1104 (530) 756-8250 FAX www.hec.usace.army.mil CPD-83

http://www.hec.usace.army.mil/

GIS Tools for Support of HEC-RAS using ArcGIS®, HEC-GeoRAS User's Manual 2009. The HEC-GeoRAS executable code and documentation are public domain software that were developed under a Cooperative Research and Development Agreement by the Hydrologic Engineering Center (HEC) and the Environmental Systems Research Institute, Inc. (ESRI) and using USACE Research and Development funding. This Hydrologic Engineering Center (HEC) documentation was developed with U.S. Federal Government resources and is therefore in the public domain. It may be used, copied, distributed, or redistributed freely. However, it is requested that HEC be given appropriate acknowledgment in any subsequent use of this work. Use of the software described by this document is controlled by certain terms and conditions. The user must acknowledge and agree to be bound by the terms and conditions of usage before the software can be installed or used. The software described by this document can be downloaded for free from our internet site (www.hec.usace.army.mil). HEC cannot provide technical support for this software to non-Corps users. In the past, for non-Corps users, HEC had provided a list of possible vendors for assistance or support for HEC software. By direction of USACE counsel HEC has discontinued this practice and has removed the list from our web site. Non-Corps individuals and organizations should use any internet search engine to locate a vendor that can provide support for the HEC software of interest. However, we will respond to all documented instances of program errors. Documented errors are bugs in the software due to programming mistakes not model problems due to user-entered data. This document contains references to product names that are trademarks or registered trademarks of their respective owners. Use of specific product names does not imply official or unofficial endorsement. Product names are used solely for the purpose of identifying products available in the public market place. Microsoft and Windows are registered trademarks of Microsoft Corp. ArcGIS, 3D Analyst, and Spatial Analyst are trademarks of Environmental Systems Research Institute (ESRI), Inc.

http://www.hec.usace.army.mil/

Table of Contents

i

Table of Contents

Foreword ............................................................................................................. v

CHAPTER 1 Intended A ......................................................... 1-2 Overview of Requirements .................................................................................. 1-2 User’s Man ... 1-3

CHAPTER 2 Software R 1 Installation 1 Loading HEC-GeoRAS ......................................................................................... 2-3

CHAPTER 3 1 Getting Sta .... 3-3 HEC-GeoRA -3 HEC-GeoRA -5 Developing ........... 3-6 Importing RAS Layers........................................................................................3-13 Generating .3-15 Running HE Processing ile......................................................................3-21

CHAPTER 4 .................... 4-1 Adding a Map .................................................................................................... 4-2 Digital Terrain Model .......................................................................................... 4-3 Background Data ............................................................................................... 4-4 Stream Centerline Layer ..................................................................................... 4-7 Cross-Sectional Cut Lines Layer ..........................................................................4-12 Bank Lines Layer ..............................................................................................4-18 Flow Path Centerlines Layer................................................................................4-19 Bridges/Culverts Layer ......................................................................................4-20 Ineffective Flow Areas Layer...............................................................................4-23 Blocked Obstructions Layer ................................................................................4-25 Land Use Layer.................................................................................................4-27 Levee Alignment Layer ......................................................................................4-30 Inline Structures Layer ......................................................................................4-34 Lateral Structures Layer.....................................................................................4-36

Introduction.......................................................................... 1-1

pplication of HEC-GeoRAS...........

ual Overview...................................................................................

HEC-GeoRAS Installation ...................................................... 2-1

equirements....................................................................................... 2-

....................................................................................................... 2-

Working with HEC-GeoRAS – An Overview............................ 3-

rted..............................................................................................

S Menus ........................................................................................... 3

S Tools............................................................................................. 3

the RAS GIS Import File ..........................................................

the RAS GIS Import File ...................................................................

C-RAS.............................................................................................3-18

the RAS GIS Export F

Developing Geometric Data...............................

Table of Contents

ii

Storage Areas Layer..........................................................................................4-39 Layer Setup .....................................................................................................4-45 Generating the RAS GIS Import File ....................................................................4-48

CHAPTER 5 GIS Data Exchange with HEC-RAS......................................... 5-1 Importing GIS Data to HEC-RAS .......................................................................... 5-1 Completing the Geometric Data ........................................................................... 5-7 Completing the Flow Data and Boundary Conditions...............................................5-11 Examining Results ............................................................................................5-11 Exporting the HEC-RAS Results...........................................................................5-12

CHAPTER 6 RAS Mapping......................................................................... 6-1 Importing the RAS GIS Export File ....................................................................... 6-1 Inundation Mapping ........................................................................................... 6-7 Velocity Mapping ............................................................................................... 6-8 Ice Thickness Mapping.......................................................................................6-11 Shear Stress Mapping........................................................................................6-11 Stream Power Mapping......................................................................................6-12 Data Storage ...................................................................................................6-12 Visualization ....................................................................................................6-13 Post-Processing Utilities .....................................................................................6-15

CHAPTER 7 Example – Data Import ......................................................... 7-1 Start a New ArcMap project................................................................................. 7-1 Generate the GeoRAS Feature Classes .................................................................. 7-2 Import Data to Feature Classes............................................................................ 7-4 Assign HydroIDs to Features ............................................................................... 7-8 Attribute Feature Classes .................................................................................... 7-9

CHAPTER 8 Example Application ............................................................. 8-1 Load HEC-GeoRAS ............................................................................................. 8-1 Start a New Project............................................................................................ 8-2 Create Contours from a DTM ............................................................................... 8-4 Create RAS Layers ............................................................................................. 8-6 Generating the RAS GIS Import File ....................................................................8-26 HEC-RAS Hydraulic Analysis ...............................................................................8-29 RAS Mapping ...................................................................................................8-46 Velocity Mapping ..............................................................................................8-53 Shear Stress Mapping........................................................................................8-55 Stream Power Mapping......................................................................................8-55

Table of Contents

iii

Ice Thickness Mapping.......................................................................................8-56

CHAPTER 9 Exampl ple DTMs ...................................................... 9-1 Start a GeoRAS project....................................................................................... 9-1

eature Class ................................................................... 9-2 9-6

Extract RAS Layers ............................................................................................ 9-6 RAS Mappin 9-6

Appendix A R Appendix B H

Spatial Dat RAS GIS Im -3 RAS GIS Ex Import/Exp Sample RA 7 Sample RA B-22

Appendix C H .. C-1 Software .. Required D .... C-2 Example ...

e – Multi

Create the Terrain Tiles F

Extract Cross Sections ........................................................................................

g.....................................................................................................

eferences .............................................................................A-1

EC-RAS Data Exchange.........................................................B-1

a Format ........................................................................................... B-2

port File (RASImport.sdf) ................................................................... B

port File (RASExport.sdf) .................................................................. B-13

ort Guidelines .................................................................................. B-15

S GIS Import File.............................................................................. B-1

S GIS Export File ..............................................................................

EC-RAS Results Interpolation .............................................

........................................................................................................ C-1

ata ...............................................................................................

........................................................................................................ C-4

Foreword

v

Foreword

on for use with ArcGIS, a general purpose

ter (HEC) and ESRI and continues to be nd Development funds. HEC-GeoRAS

Version 4 is the result of continued development by HEC and ESRI to nality of GeoRAS Version 3.1 (for ArcView 3.x) to .

iew 3.2

an.

HEC-GeoRAS is an extensiGeographic Information System software program developed and copyrighted by the Environmental Systems Research Institute, Inc., (ESRI) Redlands, California.

The HEC-GeoRAS extension was initially developed though a Cooperative Research and Development Agreement between the Hydrologic Engineering Cendeveloped using Research a

migrate the functiothe ArcGIS platform

The current HEC-GeoRAS software is based on the previous work performed at HEC by Thomas A. Evans in developing ArcInfo scripts and Cameron T. Ackerman adapting a user interface and coding enhancements. Initial development of HEC-GeoRAS for ArcVwas programmed by Dean Djokic at ESRI in the Avenue scripting language. HEC-GeoRAS 4.2 design and interface development wasperformed by Cameron Ackerman while core routines were programmed by Dean Djokic and Amit Sinha, ESRI.

Contributions from HEC staff including Gary W. Brunner, Mark R. Jensen, and comments from the field continue to shape HEC-GeoRAS development. Christopher N. Dunn was Director during the release of HEC-GeoRAS 4.2.

This manual was written by Cameron T. Ackerm

Chapter 1 Introduction

1-1

C H A P T E R 1

a for use with the Hydrologic Engineering Center’s River Analysis System (HEC-RAS). The extension allows users with limited GIS experience to create an HEC-RAS import file containing geometric

n existing digital terrain model (DTM) and complementary orted from HEC-RAS may also be processed.

ion of HEC-GeoRAS creates an import file, referred to mport File, containing river, reach and station

cut lines; cross-sectional surface lines; stream reach lengths for the left

overbank, main channel, and right overbank; and cross-sectional roughness coefficients. Additional geometric data defining levee

ctive flow areas, blocked obstructions, and storage to the RAS GIS Import File. GeoRAS Version 4,

introduced capabilities for exporting hydraulic structure data for ofile

4.2

RI Earth Explorer, and others) and the animation of floodplain results.

is manual supports HEC-GeoRAS 4.2.92 for ArcGIS 9.2 and HEC-eoRAS 4.2.93 for ArcGIS 9.3.

des an

tion of HEC-GeoRAS

Introduction

HEC-GeoRAS is set of ArcGIS tools specifically designed to process geospatial dat

data from adata sets. Results exp

The current versherein as the RAS GIS Iidentifiers; cross-sectionalcross-sectional bank stations; down

alignments, ineffeareas may be written

bridges, inline structures, and lateral structures. Water surface prdata exported from HEC-RAS may be processed into GIS data sets.

HEC-GeoRAS version 4.2 introduces new capabilities for visualizingvelocity results, shear stress results, stream power results and ice thickness data exported from HEC-RAS 4.0 or later. HEC-GeoRAS also has new tools for publishing results to a KMZ file readable by KML viewing clients (such as Google Earth, Microsoft Virtual Earth, ES

ThG

Chapter 1 discusses the intended use of HEC-GeoRAS and provioverview of this manual.

Contents • Intended Applica

• Overview of Requirements

• User’s Manual Overview


1-2

Intended Application of HEC-GeoRAS

wing of exported results from RAS. The import file is

m

e ayers.

HEC-RAS, the geometric

ported back to for spatial analysis. GIS data is

to the

HEC-GeoRAS creates a file of geometric data for import into HEC-RASand enables viecreated from data extracted from data sets (ArcGIS Layers) and froa Digital Terrain Model (DTM). HEC-GeoRAS requires a DTM represented by a triangulated irregular network (TIN) or a GRID. Thlayers and the DTM are referred to collectively as the RAS LGeometric data are developed based on the intersection of the RAS Layers.

Prior to performing hydraulic computations indata must be imported and completed and flow data must be entered.Once the hydraulic computations are performed, exported water surface and velocity results from HEC-RAS may be imthe GIS using HEC-GeoRAStransferred between HEC-RAS and ArcGIS using a specifically formatted GIS data exchange file (*.sdf) as outlined in Appendix B.

Overview of Requirements

HEC-GeoRAS 4.2 is an extension for use with ArcGIS (Environmental Systems Research Institute, 2000) that provides the user with a set of procedures, tools, and utilities for the preparation of GIS data for import into RAS and generation of GIS data from RAS output. While the GeoRAS tools are designed for users with limited geographic information systems (GIS) experience, extensive knowledge of ArcGIS is advantageous. Users, however, must have experience modeling with HEC-RAS and have a thorough understanding of river hydraulics to properly create and interpret GIS data sets.

Software Requirements

HEC-GeoRAS 4.2.92 is for use with ArcGIS 9.2 while HEC-GeoRAS 4.2.93 is for use with ArcGIS 9.3. [Previous versions of HEC-GeoRAS include v4.0 for use with ArcGIS 8.3, v4.1 for ArcGIS 9.0, v4.1.1 for ArcGIS 9.1.] Both the 3D Analyst extension and the Spatial Analyst extension are required. HEC-GeoRAS presently only runs on Microsoft Windows operating systems.

The full functionality of HEC-GeoRAS 4.2 requires HEC-RAS 4.0, or later, to import and export all of the GIS data options. Older versions of HEC-RAS may be used, however, with limitations on importing roughness coefficients, ineffective flow data, blocked obstructions, levee data, hydraulic structures, and storage area data. Further, data exported from older versions of HEC-RAS should be converted


latest XML file structure using the SDF to XML conversion tools provided.

s-sectional t

its used are those relative to the DTM coordinate system.

GeoRAS to results from :

ell as d.

ta to HEC-RAS.

d provides

Chapter 6 provides a detailed description of how to develop GIS data sets from HEC-RAS simulation results.

EC-GeoRAS geodatabase.

is an example application of how to use HEC-GeoRAS and EC-RAS to perform a river hydraulics study.

hapter 9 provides an example of using multiple terrain models in EC-GeoRAS.

Appendix A contains a list of references.

Appendix B provides the spatial data file format used by HEC-RAS for import and export with example data files.

Appendix C provides a discussion for interpolating HEC-RAS results using the stand-alone interpolator.

Data Requirements

HEC-GeoRAS requires a DTM in the form of a TIN or a GRID. The DTM must be a continuous surface that includes the bottom of the river channel and the floodplain to be modeled. Because all crosdata will be extracted from the DTM, only high-resolution DTMs thaaccurately represent the ground surface should be considered for hydraulic modeling. Measurement un

User’s Manual Overview

This manual provides detailed instruction for using HEC-develop geometric data for import into HEC-RAS and view HEC-RAS simulations. The manual is organized as follows

Chapter 1-2 provides an introduction to HEC-GeoRAS, as winstructions for installing the extension and getting starte

Chapter 3 provides a detailed overview of HEC-GeoRAS.

Chapter 4 discusses in detail the tools, methods, and darequirements for developing geometric data for import in

Chapter 5 explains how to use GIS data with HEC-RAS aan overview for completing a hydraulic model.

n

Chapter 7 is an example of how to import data into an H

Chapter 8H

CH

1-3

Chapter 2 Installation

2-1

C H A P T E R 2

Software R

patial Analyst extensions are also required. HEC-GeoRAS 4.2.92 is compiled for ArcGIS 9.2. HEC-

e with HEC-GeoRAS: Microsoft XML Parser 4.0 or later, ESRI Water Utilities Application

e

Installation

oRAS extension is installed using the HEC-GeoRAS er will detect previous versions, remove older he current version of HEC-GeoRAS and requisite

ly installed may also be Windows Control Panel using the Add/Remove

The HEC-GeoRAS installer will follow the steps listed below and provide user status in the installer dialog, shown in Figure 2-1.

1. Check that the Microsoft .NET Framework 2.0 is installed. This is required for the HEC-GeoRAS installer to run.

HEC-GeoRAS Installation

The installation procedure for the HEC-GeoRAS tools is discussed in this chapter.

Contents • Software Requirements

• Installation

• Loading HEC-GeoRAS

equirements

HEC-GeoRAS Version 4.2 requires ArcGIS 9 (ArcView license) for Windows. The 3D Analyst and S

GeoRAS 4.2.93 is compiled for ArcGIS 9.3. There are also several software components that are required for us

Framework (ApFramework), and ESRI XML Data Exchange Tools. Threquired software will be installed by the HEC-GeoRAS installer.

The HEC-Geinstaller. The installversions, and install tsoftware. Removal of software previousperformed through thePrograms option.


2-2

2. Check that correct version of ArcGIS 9 is installed and not running. ArcGIS 9.2 for HEC-GeoRAS 4.2.92 and ArcGIS 9.3 for HEC-GeoRAS 4.2.93.

3. Install the MSXML Parser 4.0 (Microsoft XML Core Services), if required.

4. Remove previous versions of the Water Utilities Application Framework, XML Data Exchange Tools, and HEC-GeoRAS.

5. Install the Water Utilities Application Framework. The Water Utilities Application Framework will be installed to the “C:\Program Files\ESRI\WaterUtils\ApFramework” directory.

6. Install the XML Data Exchange Tools. The XML Data Exchange tools will be installed to the “C:\Program Files\ESRI\WaterUtils\XMLDataTools” directory.

7. Install HEC-GeoRAS. HEC-GeoRAS will be installed to the “C:\Program Files\HEC\HEC-GeoRAS” directory.

Figure 2-1. The HEC-GeoRAS installer dialog will provide installation updates.


2-3

Loading HE

To load the GeoRAS toolbar, select Tools | Customize from the main ArcMap

C-GeoRAS

The HEC-GeoRAS tools are loaded as a toolbar in ArcMap.

interface (see Figure 2-2). Place a check in the checkbox corresponding to HEC-GeoRAS. The HEC-GeoRAS toolbar will be added to the interface. Press the Close button when finished. You may dock the toolbar where desired.

Figure 2-2. Loading the HEC-GeoRAS toolbar in ArcGIS.

Chapter 3 Working with HEC-GeoRAS – An Overview

3-1

C H A P T E

Working

ing GeoRAS software assists in the

preparation of geometric data for import into HEC-RAS and processing simulation results exported from HEC-RAS.

To create the import file, the user must have an existing digital terrain

Centerline, Flow Path Centerlines (optional), Main Channel Banks (optional), and Cross Section Cut Lines referred to, herein, as the RAS Layers.

S Layers may be created/used to extract additional geometric data for import in HEC-RAS. These layers include Land Use

ce profile data exported from HEC-RAS simulations may be nalysis.

A rview ping the RAS GIS Import File (for importing geometric data into HEC-RAS) and processing the RAS GIS

File user with the ArcGIS environment. An overview diagram of the

HEC-GeoRAS process is shown in Figure 3-1.

Contents • Getting Started

• velop

• Running HEC-RAS

• Processing the RAS GIS E

R 3

with HEC-GeoRAS – An Overview

HEC-GeoRAS is a set of procedures, tools, and utilities for processgeospatial data in ArcGIS. The

model (DTM) of the river system in a TIN or GRID format. The user creates a series of point, line, and polygon layers pertinent to developing geometric data for HEC-RAS. The line layers created are the Stream

Additional RA

(for Manning’s n values), Levee Alignments, Ineffective Flow Areas, Blocked Obstructions, Bridges/Culverts, Inline Structures, Lateral Structures, and Storage Areas.

Water surfaprocessed by HEC-GeoRAS for GIS a

n ove of the steps in develo

Exportthe

(results exported from HEC-RAS) is provided to familiarize

De ing the RAS GIS Import File

xport File


3-2

RAS. Figure 3-1. Process flow diagram for using HEC-Geo


3-3

Getting Sta

s

When the HEC-GeoRAS extension loads, menus and tools are y

nded

exported HEC-RAS simulation results. The HEC-GeoRAS toolbar is shown in Figure 3-2.

rted

Start ArcMap. Load the HEC-GeoRAS tools by selecting Tools | Customize from the main ArcMap interface and placing a checkboxnext to HEC-GeoRAS. The Spatial Analyst and 3D Analyst extensionwill automatically load whenever required by the tools.

automatically added to the ArcMap interface. Menus are denoted btext and tools appear as buttons. These menus and tools are inteto aid the user in stepping through the geometric data development process and post-processing of

Figure 3-2. The HEC-GeoRAS toolbar.

HEC-GeoRAS Menus

The HEC-GeoRAS menu options are RAS Geometry, RAS Mapping, ApUtilities, and Help. These menus are discussed below.

RAS Geometry

The RAS Geometry menu is for pre-processing geometric data for import into HEC-RAS. Items are listed in the RAS Geometry dropdown menu in the recommended (and sometimes required) order of completion. Items available from the RAS Geometry menu items are shown in Figure 3-3.


3-4

Figure 3-3. GeoRAS geometry processing menu items.

S

ion. Items available from the

RAS Mapping

The RAS Mapping menu is for post-processing exported HEC-RAresults. Items available from the RAS Mapping dropdown menu are listed in the required order of completRAS Mapping menu are shown in Figure 3-4.

Figure 3-4. RAS Mapping menu items.


3-5

ApUtilites

Features available from the ApUtilities menu are uscenes to manage the data layers created throavailable from the ApUtilities menu is functionalitHydroID to features. Only experienced users the ApUtilites menu.

You MUST add new Data Frames (Maps) usAdd New Map menu item. Otherwise GeoRAS w

sed behind the ugh GeoRAS. Also

y to assign a unique should use the items on

ing the ApUtilites | ill not find the

version is consistent with the ArcGIS product it is being

used with!

HEC-GeoR

nvoke a dialog or change

the mouse pointer, indicating the need for further action.

Table 3-1. Summary of HEC-GeoRAS tools.

proper data sets to work with!

Help

The Help menu will provide general online help information and will provide the version number. Use the “About HEC-GeoRAS” menu itemto verify the

AS Tools

There are several tools provided in the toolbar. A tool waits for useraction after being activated and will either i

Tool Description

network. Allows the user to assign River and Reach names to the stream

Allows the user to assign station values to a stream endpoint.

Assigns a LineType (Left, Channel, Right) value to the Flow Paths feature class.

Generates cross-sectional cut lines perpendicular to a streamcenterline at a specified interval.

Interactively plots a selected cross section.

Assigns elevation values to a levee alignment for interpolation.

Converts HEC-RAS output in SDF format to XML file. Necessary prior to post-processing RAS results.


3-6

Developing the RAS GIS Import File

The main steps in developing the RAS GIS Import

• Start a New Project

• Create RAS Layers

• Generate the RAS GIS Import File

File are as follows:

Start a new project by opening a new ArcMap document. You should

ory that has no wild card characters in the pathname. Post-processing functions for the depth grids may not work if there are wild

at. To load the Terrain DTM,

Start a New Project

then save the ArcMap project to an appropriate directory before creating any RAS Layers. (You will save your ArcMap project to a direct

cards in the pathname to the grids.) This may require using the filebrowser to create and name a new directory. The directory to which the ArcMap project is stored becomes the default location where the RAS geodatabase is created and the location where the RAS GIS Import File is written.

Next, load the DTM in TIN/GRID form

press the (Add Layer) button on the ArcMap interface. This invokes a browser. Select the TIN/GRID dataset and press OK. The DTM is added to the c rent map.

Create RAS Layers

ur

The next step is to create the RAS Layers that will be used for elopment and extraction. The layers that need to Stream Centerline, Banks (optional), the Flow Path

s. Optional te Manning’s n

of inline structures; a polyline layer of lateral structures; and a

vert/import them to a feature

r to add this field and populate HydroID values.

geometric data devbe created are the Centerlines (optional), and the Cross Section Cut Linelayers include: a polygon layer of land cover to estimavalues; a polyline layer of levee alignments; a polygon layer for representing ineffective flow areas; a polygon layer for representing blocked obstructions; a polyline layer of bridges/culverts; a polyline layer polygon layer for floodplain storage areas.

Existing shapefiles or ArcInfo coverages may be used; however, theywill need to contain the required database fields. If shapefiles or ArcInfo coverages are used, always conclass, as discussed in Chapter 7. The existing layers must have a HydroID field populated for them to be useful. You can use the HydroID tool from the ApUtilities menu or the ArcHydro toolba


3-7

One simple way to ensure that that your data set has the required fields of the GeoRAS geodatabase design is to create an empty feature

Feature Class (where Feature Class corresponds to a RAS Layer) menu items

nto an existing geodatabase will allow you to import attribute data. An example on importing data is provided in Chapter 7.

t procedure. The following section provides an overview for creating the RAS Layers.

Stream Centerline

The Stream Centerline layer should be created first. Select the RAS item as

class using the RAS Geometry | Create RAS Layers |

and copy and paste the features from your existing data set. This action however, will not populate the attributes. Importing existing data i

Feature layers are created using basic ArcGIS editing tools. The GeoRAS RAS Geometry menu directs the user through the data developmen

Geometry | Create RAS Layers | Stream Centerline menushown in Figure 3-6.

Figure 3-5. Create RAS Layers menu items.


3-8

The dialog shown in Figure 3-6 will appear. Enter the layer name (or accept the default name) and press OK.

Figure 3-6. Create Stream Centerline layer dialog.

The Stream Centerline layer is added to the Map. To start adding features to the Stream Centerline layer you will need to start an edit session on the feature class.

Editing is done usinloaded by selectin

g the Editor toolbar. Ensure the editing toolbar is g the Tools |Customize menu item and placing a

in Figure 3-7 will be added to the interface. checkbox next to the Editor toolbar. The toolbar shown

e (or shapefiles), a dialog will prompt you to choose the geodatabase you wish to edit. Once you

etch tool and begin drawing the river reaches one by one on the map. River reaches must be drawn from upstream to

having a series of vertices. After creating the river network, save your edits

g).

yer, however, is not complete until each River

Figure 3-7. Editor toolbar in ArcGIS.

Select the Editor | Start Editing menu item. If you have layers loaded from more than one geodatabas

have selected the geodatabase, you must select the Target feature class (layer) you wish to edit and select the Task (Create New Feature, Modify Feature, etc).

Lastly, select the Sk

downstream. Each river reach is represented by one line

(Editor | Save Edits) and stop editing (Editor | Stop Editin

The Stream Centerline la

and Reach has been assigned a name. Select the (Reach anRiver ID) tool. Cross hairs will appear as the cursor is moved overthe map display. Use the mouse to select a River Reach. The dialoshown in Figure 3-8 will be invoked allowing you to name the river an

d g

d reach. Previously specified river names are available from a drop down

each list using the down arrow to the right of the river name field. Rnames for the same river must be unique.


3-9

Main Channel Banks

nks layer is optional. If you do not create s in

HEC-RAS.

nu e and press OK.

s

layer is optional. If omitted, distances between cross-sections will need to be added manually

nterface.

Select the RAS Geometry | Create RAS Layers | Flow Path

Figure 3-8. River and reach name assignment.

Creating the Main Channel Bathe banks layer, you will need to define the bank station location

Select the RAS Geometry | Create RAS Layers | Bank Lines meitem. Enter the layer nam

Start editing and draw the location of the channel banks. Separate lines should be used for the left and right bank of the river. Bank linefrom tributary rivers may overlap the bank lines of the main stem. After defining each bank line, save edits.

Flow Path Centerlines

Creating the Flow Path Centerlines

through the HEC-RAS i

Centerlines menu item. Enter the layer name and press OK.

If the Stream Centerline layer exists, the stream centerline is copied as the flow path for the main channel. Each flow path must be labeled with an identifier of Left, Channel, Right, corresponding to the left

overbank, main channel, or right overbank. One by one, use the (Flowpath) tool to label each flow path. After activating the Flowpatool, select each flow path with the c

th ross-hairs cursor. The dialog

shown in Figure 3-9 will appear allowing the user to select the correct flow path label from a list.


3-10

Figure 3-9. Label the Flow Path Lines with Left, Channel, or Right.

Cross-Sectional Cut Lines

Select the RAS Geometry | Create RAS Layers | XS Cut Lines menu item. Enter the layer name in the dialog that appears and press OK.

Start editing and use the Sketch tool to draw the locations where cross-sectional data should be extracted from the terrain model. Each cross-sectional cut line should be drawn from the left overbank to the

oss-sectional cut lines are dicular to the flow

Cross sections can be generated automatically at a specified interval

and width using the

right overbank, when facing downstream. Crmulti-segment lines that should be drawn perpenpath lines. Cut lines must cross the main channel only once and no two cross sections may intersect.

(Construct XS Cut Lines) tool. This is NOT

uidelines necessary for modeling one-dimensional flow (i.e. cross sections could end up crossing each

drawn from the left overbank to the right overbank, when facing downstream.

he next in the Bridge/Culvert attribute table.

the preferred method and should be used with caution because the lines are not generated following the g

other and the main channel multiple times).

Bridges/Culverts

Creating the Bridge/Culvert feature class is optional.

Select the RAS Geometry | Create RAS Layers | Bridges/Culverts menu item. Enter the layer name in the dialog that appears and press OK.

Start editing and use the sketch tool to draw the locations where bridge deck data should be extracted from the terrain model. Each deck cut line should be

You will also need to specify the top width and distance to tupstream cross section


3-11

Ineffective Areas

Creating the Ineffective Areas feature class is optional.

| Create RAS Layers | Ineffective Areas menu item. Enter the layer name in the dialog that appears and press

ound areas that should be modeled as ineffective. Ineffective areas should be

s where flow is expected to stagnate.

s

te RAS Layers | Blocked Obstructuions menu item. Enter the layer name in the dialog that appears and press OK.

ool to draw polygons around areas that should be modeled as blocked out from flow. Blocked

Select the RAS Geometry

OK.

Start editing and use the sketch tool to draw polygons ar

used near bridge abutments and other area

Blocked Obstruction

Creating the Blocked Obstructions feature class is optional.

Select the RAS Geometry | Crea

Start editing and use the sketch t

obstructions should be used in areas where there has been floodplainencroachment.

Levee Alignments

Creating the Levee Alignments feature class is optional.

Select the RAS Geometry | Create RAS Layers | Levee Alignment menu item. Enter the layer name in the dialog that appears and press OK.

Start editing and use the sketch tool to draw the alignment of the levee. Elevation data may be provided along the levee using the Levee Tool or GeoRAS will use the elevation data from the DTM. Levees should be along high areas such as levees, roads, and ridges that prevent flow from flowing out into the floodplain.

Land Use

Creating the Land Use layer and estimating n values is optional.

If you choose to use this layer, you will need to create a data set that covers the entire extent of each cross section. Further, you may not use a polygon data set that is MULTIPART. Using the “clipping” feature of ArcMap is useful feature for creating polygons that share a common edge.


3-12

Land use data may be used to estimate Manning’s n values for each cross section. Select the RAS Geometry | Create RAS Layers | Land Use menu item. Enter the layer name in the dialog that appears

to draw polygons around areas that you want to represent with a single roughness coefficient. If you

d

Inline Structures

menu item. Enter the layer name in the dialog that appears and press

e

to specify the top width and distance to the next upstream cross section in the Inline Structures attribute table.

and press OK or load the land use layer from an existing data set.

Start editing and use the sketch tool

have a field with the name “N_value”, enter the corresponding roughness coefficients for each polygon.

If you have an existing data set that has a descriptive field you can link roughness values to, you will need to create a linked table using the RAS Geometry | Manning’s n Value | Create LU-Manning Table menu item. Enter the roughness estimate in the “N_value” fielbased on the linked description.

Creating the Inline Structures feature class is optional.

Select the RAS Geometry | Create RAS Layers | Inline Structures

OK.

Start editing and use the sketch tool to draw the locations where inlinstructure data should be extracted from the terrain model. Each inline structure cut line should be drawn from the left overbank to the right overbank, when facing downstream.

You will also need

Lateral Structures

Creating the Lateral Structures feature class is optional.

Select the RAS Geometry | Create RAS Layers | Lateral Structures menu item. Enter the layer name in the dialog that appears and press OK.

Start editing and use the sketch tool to draw the locations where lateral structure data should be extracted from the terrain model. Each lateral structure cut line should be drawn in the downstream direction.

You will also need to specify the top width and distance to the upstream cross section just upstream in the Inline Structures attribute table.


3-13

Storage Areas

Creating the Storage Areas feature class is optional.

Select the RAS Geometry | Create RAS Layers | Storage Amenu item. Enter the layer name in the dialog that appears and press OK.

reas

s

rbank to the right overbank, when facing

Importing R

ho fied

tically populated.

u re class

Start editing and use the sketch tool to draw polygons around areathat will act as floodplain storage.

Storage Area Connections

Creating the Storage Area Connections feature class is optional.

Select the RAS Geometry | Create RAS Layers | Storage Area Connections menu item. Enter the layer name in the dialog that appears and press OK.

Start editing and use the sketch tool to draw the locations where the storage area connection data (weir profile) should be extracted from the terrain model. Each storage area connection should be drawn from the left ovedownstream.

You also need to attribute the connections with the nearest storage areas and weir’s top width.

AS Layers

The other option to creating a layer is to import an existing layer, andassign a HydroID value to each feature. The HydroID field is requiredfor the GeoRAS tools to work. This is particularly useful for users walready have layers containing all the required fields in the speciformat, though it is probably better to import the basic RAS Layers, assign attributes, and then create the associated 3D layers using the GeoRAS tools. If these layers are created in GeoRAS, the HydroIDfields are automa

The HydroID field could be created and values assigned through the HydroID tool in the ApUtilites menu shown in Figure 3-10. The menitem will invoke a dialog that allows the user to specify a featu(RAS Layer) and assign unique HydroIDs. If the HydroID field does not exist, the field will be created. Note that HydroID values mustbe assigned prior to attributing any of the feature classes. TheHydoID provides the link from each feature to an attribute in an associated table.


3-14

To migrate a shapefile to a geodatabase, perform the following steps (for a more detailed example refer to the data import example in Chapter 7):

1. Start ArcCatalog.

2. Navigate to the dataset in the personal geodatabase where you want to import the shapefile.

3. Right click on the dataset, click on Import | Shapefile to Geodatabase Wizard tool. Select the shapefile. Click on Next.

4. Enter the desired feature class name. Click on Next button.

5. Instead of using defaults, elect to specify the remaining parameters. Keep clicking on Next buttons. You will be offered to change the Spatial Index Grid, Item to Field Mapping, and Current Spatial Reference. On the Item to Field Mapping page, change the names of field to the names desired.

6. Click on Finish to complete data migration from shapefile to geodatabase.

An alternative (simple) route is to perform the following:

1. Start ArcMap.

Figure 3-10. Assign Unique HydroIDs menu item is on the ApUtilites menu.

Importing Shapefiles to a Geodatabase


3-15

2. Create the feature class of interest using the GeoRAS RAS Geometry | Create RAS Layers | Feature Class. This creates all the require fields.

3. Add the shapefile.

4. Select all the features in the shapefile.

5. Copy the features to the clipboard (Edit | Copy).

6. Start Editing the new feature class.

7. Paste the features into the feature class (Edit | Paste).

8. Stop Editing.

9. Attribute the feature class using the GeoRAS tools provided or enter the data by hand. (You may need to repeat Steps 3-7 for multiple feature classes.)

Generating the RAS GIS Import File

After creating/editing each RAS Layer, select the RAS Geometry | Layer Setup menu item. The pre-processing layer setup dialog shown in Figure 3-11 allows you to select the RAS Layers used for data development and extraction. There are several tabs with dropdown lists. Click through each tab and select the corresponding data.

Figure 3-11. Layer Setup dialog for pre-processing RAS Layers.


3-16

From the Required Surface tab, select the terrain data type: TIN or GRID. Use the drop down lists to select the Terrain TIN/GRID.

From the Required Data tab, verify that the Stream Centerline layer and XS Cut Lines layer are selected. The XS Cut Line Profiles will be created by GeoRAS in a later step.

From the Optional Layers tab, verify/select the layers you have created. Press the OK button when finished.

Next, select the RAS Geometry | Stream Centerline Attribute | Topology menu item. This process completes the centerline topology by populating the FromNode and ToNode fields. In addition, a table is also created to store nodes x, y, and z coordinates. These are used later to create the GIS import file. Select RAS Geometry | Stream Centerline Attribute | Length/Stations to assign length and station values to river features.

Optionally, select RAS Geometry | Stream Centerline Attribute | Elevations to create 3D stream centerline layer from the 2D layer using elevations from the DTM. This step is not required – HEC-RAS does not use the elevation data extracted along the stream centerline!

The next step is to add geometric attributes to the Cross Section Cut Line layer. Select the items under the RAS Geometry | XS Cut Line Attributes menu one-by-one verifying the data that is appended to the XS Cut Line attribute table after each step. If an error message is invoked, fix your data set, and repeat the menu item. River and reach names, river station, bank station (optional), and downstream reach length (optional) information will be appended to each cross section cut line.

To complete the cross-sectional data, station-elevation data needs to be extracted from the DTM. Select the RAS Geometry | XS Cut Line Attributes | Elevations menu item. This will create a 3D cross-sectional surface line layer from the cross-sectional cut lines.

If you have a Land Use layer with estimated roughness coefficients, select the RAS Geometry | Manning’s n Values | n Values Extract to determine the horizontal variation in Manning’s n values along each cross section. An option to either use a summary Manning table or directly use an N_Value field from a Land Use layer is available. Thus, if the Land Use layer already has the Manning field populated, you can directly use the Land Use layer as the source of Manning’s n values to create a table listing cross-section segments and its manning value.

If the Manning n Values | Create LU-Manning table tool is used, an option to choose the field to cross-reference for Manning’s n values from the Land Use layer is added. A summary Manning table is created with empty Manning’s n values and you will have to manually enter them.


3-17

If you have the Levee layer, select RAS Geometry | Levee | Profile Completion to create 3D Levee features from the 2D features using

is tool will optionally apply the user-Points feature class to interpolate the

Levee elevations. Select RAS Geometry | Levee | Positions to

ct the RAS Geometry | ons to calculate the location of

ineffective flow areas at the cross sections.

elect the RAS Geometry | mes to assign the River and

ometry |

mes that the Inline Structures intersects. Select the RAS Geometry | Inline Structures | Stationing to assign station values

ns

by extracting elevations from the DTM.

-

erefore, skipping this step is recommended.)

al information contained in the XS Cut Line Profiles layer to the RAS GIS

,

the DTM as source of elevation. Thdefined elevations from the Levee

calculate the intersection of the levees at the cross sections.

If you have ineffective flow data, seleIneffective Flow Areas | Positi

If you have a Bridges/Culverts layer, sBridges/Culverts | River/Reach NaReach Names to the feature from the Stream Centerline layer. Select the RAS Geometry | Bridges/Culverts | Stationing to assign riverstation values to the Bridge/Culvert features. Select the RAS Geometry | Bridges/ lverts | Elevations to create a 3D layer by extracting elevations from the DTM.

If you have an Inline Structures layer, select the RAS GeInline Structures | River/Reach Names to assign the River and Reach Na

Cu

to the Bridge/Culvert features. Select the RAS Geometry | Inline Structures | Elevations to create a 3D layer by extracting elevatiofrom the DTM.

If you have a Lateral Structures layer, select the RAS Geometry | Lateral Structures | River/Reach Names to assign the River and Reach Names that the Lateral Structure lies along. Select the RAS Geometry | Lateral Structures | Stationing to assign station values to the Bridge/Culvert features. Select the RAS Geometry | Lateral Structures | Elevations to create a 3D layer

If you have storage areas, select the RAS Geometry | Storage Areas | Elevation Range to calculate the minimum and maximum elevation. Select the RAS Geometry | Storage Areas | ElevationVolume Data to calculate elevation-volume relationship for each storage area of interest. Optionally. Select the RAS Geometry | Storage Areas | TIN Point Extraction to extract all TIN points that fall within the storage area. (HEC-RAS does not currently use the points extracted within the Storage Area, th

Lastly, select the RAS Geometry | Extract GIS Data menu item. This step writes the header information, river and reach information contained in the Stream Centerline layer, and cross-section

Import File in the HEC-RAS spatial data format. Manning’s n values, levee alignment data, ineffective flow data, blocked obstruction databridge/culvert data, inline structure data, lateral structure data, and storage data will be written, if available. This tool generates the RAS


3-18

GIS import file in two formats: one in the SDF format and the otthe XML format. The XML format is designed for future use. Note that this tool uses predefined XML and XSL files located under the “binfolder in the HEC-GeoRAS install folder. These files are automatically installed, and must not be moved by the user. The tool expects to these files at this location.

her in

”

find

Running HEC-RAS

Create and save a new HEC-RAS project. From the Geometric Schematic choose the File | Import Geometry Data | GIS Data menu option. Select the .RASImport.sdf file to import. The Import Option dialog will appear as shown in Figure 3-12, though the dialog will be set to the Intro tab. Select the unit system to import the data into. Next, select the stream centerline by River and Reach name to import. Then select the cross sections to import by placing a check in the corresponding box. Select the properties to import for each cross section. When finished identifying the data for import press the Finished – Import Data button.


3-19

Figure 3-12. HEC-RAS geometric data import options dialog.

on ary. Hydraulic data that may not

be imported includes hydraulic structure data, ineffective flow areas, levees locations, blocked obstructions and storage areas. Flow data

tions need to be supplied, as well. importing geometric data, refer to

g e

Manual, Chapter 13 (Hydrologic Engineering Center, 2009).

After importing the geometric data extracted from the GIS, completiof the hydraulic data will be necess

and the associated boundary condiFor a more complete discussion onthe section devoted to using HEC-RAS or the HEC-RAS User’s Manual, Chapter 13 (Hydrologic Engineering Center, 2009).

After running various simulations in HEC-RAS, export the results usinthe File | Export GIS Data dialog on the main HEC-RAS window (seFigure 3-13). For a more complete discussion on exporting GIS data, refer to the HEC-RAS User’s


3-20

Figure 3-13. HEC-RAS dialog for exporting water surface profile result to the GIS.


3-21

Processing the RAS GIS Export File

The main steps in processing HEC-RAS results are as follows:

• Reading the RAS GIS Export File

• Processing RAS Results Data

Reading the RAS GIS Export File

The first step to importing HEC-RAS results into the GIS is to convert the SDF output data into an XML file, because the GeoRAS only use

this format. Click the (Convert RAS SDF to XML) button to execute this task. This tool initiates an external executable program, named SDF2XML.exe located under the “bin” folder, and dialog shown in Figure 3-14 will appear. Select the RAS GIS Export File (.RASExport.sdf) in the. Click on the OK button convert this file to XML format.

Figure 3-14. Convert HEC-RAS output file (*.sdf) to XML file dialog.

The next step to importing HEC-RAS results into the GIS is to setup Select the RAS

wn in Figure 3-15 alysis or re-run an analysis, the variables

For a new analysis, you xport File, terrain

e, dataset name, and a

may not have also be less than 128 cludes the TIN name

isk is specified in the layers data source property. Each new analysis requires a new directory.

the necessary variables for post RAS analysis. Mapping | Layer Setup menu item. The dialog showill appear to allow you to either start a new anexisting analysis. When you re-run an existing input in the layer setup cannot be changed. need to specify a name for the analysis, RAS GIS ETIN/GRID, output directory, output geodatabasrasterization cell size.

Note that the output directory path and name wild card characters. The pathname must characters when using TIN models (this inand subsequent file names used to create the TIN).

The names of water surface TINs and floodplain GRIDs are hardwired in GeoRAS, and it is recommend that these names not be changed. The name of the feature class on d


3-22

The RAS GIS Export File is the XML export file generated in the previous step. Some post-processing results such as water surface tin and flood delineation grid will be saved into the output directory. Vector data generated in post-processing will be saved into the dataset within the specified geodatabase. The rasterization cell size will beused in grid calculations.

Figure 3-15. Layer setup dialog for post-processing HEC-RAS results.

To create preliminary data sets that are essential to post processing, select the RAS Mapping | Read RAS GIS Export File menu item.

HEC-GeoRAS will read the export file and begin creating preliminary data sets. Preliminary feature classes created include the following:

• Cross section cut lines – “XS Cut Lines” layer

• Bounding polygon for each water surface profile – “Bounding Polygons” layer

These two data sets are created without user input and will be used later for building floodplain data sets. For each new analysis, a new data frame is created that is named after the Analysis. A separate

d as specified in the Layer Setup. A new personal geodatabase is created under this directory and it shares the same directory is require

name as the Analysis and data frame (map).


3-23

The name of the dataset in the geodatabase by default is “RASResults”. This is hardwired in GeoRAS. The “RASResults” datasecontains the cross section cut l

t ines and bounding polygon layers that

will be used in further analysis. After the “RASResults” data set is

gon successfully created, a new map (data frame) with the name of the Analysis is created. Both cross-sectional cut line and bounding polylayers are added to the map as feature layers (see Figure 3-16).

and processed from the RAS GIS Import File.

Processing RAS Results Data

Post-processing of RAS results creates GIS Layers for inundation and velocity analysis. All GIS Layers developed during RAS post-processing are based on the content of the RAS GIS Export File and the Terrain TIN/GRID. For data consistency, the same Terrain TIN/GRID used for generation of the RAS GIS Import File should be used for post-processing.

Inundation Results

Once the RAS GIS Export File has been read, the user can begin creating inundation data sets. The first step is to create water surface

Figure 3-16. Base data read in

Additional data for the bank stations, water surface extents, velocities, and ice thickness will be read in and feature classes created, if the data exists in the RAS Export file.


3-24

TINs for each water surface profile. Select the RAS Mapping | Inundation Mapping | Water Surface Generation menu item. This will invoke a dialog shown in Figure 3-17 with a pick list of water surface profile names. Multiple water surface profiles may be selected by holding the SHIFT key down during selection. Press OK to build the water surface TINs.

Figure 3-17. Water surface profile TIN selection dialog.

One water surface TIN will be created for each selected water surface profile. The TIN is created based on the water surface elevation at each cross section and the bounding polygon data specified in the RAS GIS Export File. The water surface TIN is generated without considering the terrain surface. The water surface TINs created will be named as a concatenation of “t” and the water surface profile name (e.g., “t 100yr”); and they will be saved into the output directory specified in the Layer Setup.

After a water surface TIN has been created, it is added to the map. An example is provided in Figure 3-18.


3-25

d for each water surface profile and added

p. Water surface profile names are prefixed with a "t".

each water surface profile RAS Mapping |

is will ion dialog to pick from the water surface profile names.

be selected by holding the SHIFT ult, the option to perform a be selected. Press OK to build

Figure 3-18. Water surface TINs are generateto the ma

The floodplain may then be delineated forfor which a water surface TIN exists. Select the Inundation Mapping | Floodplain Delineation menu item. Thinvoke a selectMultiple water surface profiles maykey down during selection. By defa“Smooth Floodplain Delineation” willfloodplain polygon feature classes.

Figure 3-19. Selection dialog for performing floodplain delineation provides an option for a "Smooth Floodplain Delineation".


3-26

A floodplain polygon will be created based on the water surface profile TIN that was created previously. Each floodplain polygon results from

the water surface and terrain surface. The water surface to grids with the same cell size and

id is then created with values where the water the terrain grid. The depth grid is then polygon to remove area not included in the

. Each depth grid is named as a concatenation rofile name (e.g., “d 100yr”); and it is

irectory specified in the Layer Setup. The depth to a floodplain polygon feature class that is

ified dataset of the personal geodatabase. The e named as a concatenation of “b” and

.g., “b 100yr”).

depth grid and floodplain boundary he map having the same name of dataset . Figure 3-20 presents an example of the

intersectingTIN and Terrain TIN are convertedorigin. A depth grsurface grid is higher thanclipped with the boundingriver hydraulics modelof “d” and the water surface psaved into the output dgrid is then converted inalso saved in the specfloodplain boundary polygons arthe water surface profile name (e

After the floodplain delineation, thefeature class are added to tspecified in the Layer Setupfloodplain boundary feature class.

C-.

This will invoke a selection dialog to pick from the water surface profile

Figure 3-20. Floodplain delineation creates depth grids prefixed by "d" and floodplain boundary feature class prefix with a "b".

Velocity Results

Velocity results exported from HEC-RAS may be visualized using HEGeoRAS. Select the RAS Mapping | Velocity Mapping menu item


3-27

names. MultipSHIFT key dow

le water surface profiles may be selected by holding the n during selection. Press OK to create the individual

velocity grids for each profile.

nt

er

Ice thickness results exported from HEC-RAS may be visualized using

file

HEC-RAS may be visualized using he RAS Mapping | Shear Stress Mapping

menu item. This will invoke a selection dialog to pick from the water

-RAS may be visualized using HEC-GeoRAS. Select the RAS Mapping | Stream Power Mapping menu item. This will invoke a selection dialog to pick from the water

rofile names. Multiple water surface profiles may be selected g the SHIFT key down during selection. Press OK to create

ofile.

A velocity grid for each profile is created based on the floodplain poivelocities and the previously computed floodplain boundary. The raster dataset is added to the map. Each depth grid is named as a concatenation of “v” and the water surface profile name (e.g., “v 100yr”); and it is saved into the output directory specified in the LaySetup.

Ice Thickness Results

HEC-GeoRAS. Select the RAS Mapping | Ice Mapping menu item. This will invoke a selection dialog to pick from the water surface pronames. Multiple water surface profiles may be selected by holding theSHIFT key down during selection. Press OK to create the individual icegrids for each profile.

Shear Stress Results

Shear stress results exported fromHEC-GeoRAS. Select t

surface profile names. Multiple water surface profiles may be selectedby holding the SHIFT key down during selection. Press OK to create the individual shear stress grids for each profile.

Stream Power Results

Stream power results exported from HEC

surface pby holdinthe individual shear stress grids for each pr

Chapter 4 Developing Geometric Data

4-1

C H A P

ary to oss-sectional elevation

n Model (DTM) of the e, while cross-sectional properties

RAS Layers. The DTM

enterline and XS Channel Banks, Flow

ve Areas, Blocked Obstructions and Storage Areas. Hydraulic structure layers may also be created for Bridges/Culverts, Inline Structures and Lateral

culvert cut line locations and elevation profiles;

• Inline and lateral structure locations and elevation profiles;

e area locations and elevation-volume relationships; and

• Storage area connection locations and elevation profiles.

GIS

T E R 4

Developing Geometric Data

The RAS GIS Import File consists of geometric data necessperform hydraulic computations in HEC-RAS. Crdata are derived from an existing Digital Terraichannel and surrounding land surfacare defined from points of intersection betweenmay be in the form of a TIN or GRID.

Required RAS Layers created include the Stream Cut Lines. Optional RAS Layers include the Main

C

Path Centerlines, Land Use, Levee Alignment, Ineffecti

Structures. Geometric data and cross-sectional attributes are extracted to generate a data file that contains:

• River, reach, station identifiers;

• Cross-sectional cut lines and surface lines;

• Main channel bank station locations;

• Reach lengths for the left overbank, main channel and right overbank;

• Roughness coefficients;

• Levee positions and elevations;

• Ineffective flow areas and obstructions to flow;

• Bridge/

• Storag

Expansion/contraction coefficients are not written to the RASImport File.

Chapter 4 discusses the data layers and steps required to develop theRAS GIS Import File.


4-2

Contents

• Stream Centerline Layer

• Lateral Structures Layer

• Layer Setup

Adding a

cMap document ame of the map

on as the .mxd file. new map.

s will register the map ystem.

document, set the ordinate system through

stem tab. The define the coordinate do not set the coordinate model (provided it has be used to determine E: all RAS Layers

e in the same coordinate system!

• Adding a Map

• Digital Terrain Model

• Background Data

• XS Cut Lines Layer

• Bank Lines Layer

• Flow Paths Centerline Layer

• Land Use Layer

• Levee Alignment Layer

• Bridges/Culverts Layer

• Ineffective Flow Areas Layer

• Blocked Obstructions Layer

• Inline Structures Layer

• Storage Areas Layer

• Storage Area Connections Layer

• Generating the RAS GIS Import File

Map

Prior to using GeoRAS, you need to save the Ar(.mxd). Data you create will be based on the ndocument and will be stored in the same locatiSelect the ApUtilities | Add Map menu item to add aEnter a map name and press OK. The ApUtilitiewith the behind-the-scenes data management s

Once the Map has been added to the ArcMap coordinate system for analysis. Access the cothe map Properties and the Coordinate Sycoordinate system of the map will be used to system for each RAS Layer you create. If yousystem it will be set when you load the terrainprojection information). The terrain model willthe spatial extent for the each RAS Layer. NOTand terrain model must b


4-3

Digital Terr

l

is

es, such as channel banks, roads, and levees. The terrain model should be constructed to completely depict the floodplain of interest from elevation point data and

g linear features of the landscape. Elevation data om the DTM for each cross section. The DTM will

also be used for floodplain mapping – to determine floodplain

tric

geometry. Channel geometry typically dictates flow in river systems; ry

f the river hydraulics as governed by the terrain.

Tiles Layer

r

large terrain model. Note that ill n

if possible, and not at confluences.

t exist containing a record for each e bounds of the terrain model.

single DTM.

ain Model

HEC-GeoRAS requires an existing DTM that represents the channebottom and the adjacent floodplain areas. The DTM may be in the form of a triangulated irregular network (TIN) or a GRID. A TIN is thepreferred method for surface modeling for river hydraulics because it well suited to represent linear featur

breaklines identifyinwill be extracted fr

boundaries and to calculate inundation depths.

Developing a good hydraulic model begins with an accurate geomedescription of the surrounding land surface, especially the channel

therefore, only highly accurate DTMs describing the channel geometshould be considered for the basis of performing hydraulic analysis. Further, RAS Layers should be created with thoughtful evaluation o

Terrain

GeoRAS offers the capability to use a single DTM of the study area omultiple DTMs. Predominantly, this documentation assumes that youare using a single DTM; however multiple DTMs may be required if the size of the study area results in a veryeven when using multiple DTMs, there are file size limitations that wbe evident during floodplain mapping and may require the delineatioto occur over several separate reaches. An example for use of multiple DTMs is provided in Chapter 9.

Rules! • Multiple DTMs exist for the study area.

• DTMs should overlap to properly represent the terrain surface at the edge of each terrain model (necessary for TIN models).

• DTMs should break at straight river reaches,

• A polygon feature class musterrain tile that represents th

• Each RAS Layer feature (cross section cut line, lateral structure, storage area, etc) must be contained within one bounding polygonfeature so that elevation data may be extracted from a


4-4

Creating the Terrain Tiles Layer

The polygon feature class is created by GeoRAS using the Geometry | Create RAS Layers | Terrain Tilesfields for the polygon feature class that will nprovided in Table 4-1.

RAS . The definitions of

eed to be completed are

Table 4-1. Polygon feature attributes.

Field Description

HydroID Long Integer – A unique feature identifier.

TileName String – Name of the TIN or GRID.

TileDirectory String – Directory where the terrain model is located.

TerrainType Short Integer – Indicates whether the terrain model is a TIN or GRID (0=GRID, 1=TIN).

Creating Terrain Tiles from a Single DTM

Large terrain models are not handled very efficiently by ArcGIS. There i the nd the ESRI Grid format doesn’t efficiently compress “NoData” cells. This results in large datasets thal a files.evident during the n delineation process.

On s is to “tile” the terrain model. T taset several smaller (more manageable) datasets. HEC-GeoRAS provides a method f her n the extents of features within the Terrain Tiles Layer.

rain Tiles Layer and digitize the extents of what will be the new smaller

step during the RAS Mapping process.

e”, and “TileDirectory”. If the output

s a limit on number of points that can be used in an ESRI TIN a

t cannot be process by GeoRAS and/or Difficulties with large datasets become especially

floodplaiarge dat

e method of handling large datasetiling a da results in breaking the large dataset up into

or tiling eit TINs or Grids by creating grids based o

To create terrain tiles from a single terrain dataset, create the Ter

terrain datasets. Select the RAS eometry | Terrain Tiles | Extract TIN/GRID menu option. In the dialog provided (shown in Figure 4-1), select the input and output parameters. Note that the user is provided the option to output TIN or Grid datasets (if a TIN is the Terrain source). It is suggested that the output datasets should be in the Grid format for floodplain mapping, as it will preempt the conversion

G

The terrain tiles will be created in the specified output directory andthe Terrain Tiles Layer attributes will automatically be populated withthe “TerrainType”, “TileNamdatasets are of the gridded format, the tiles will be registered such that the grid cells from overlapping tiles are aligned.


4-5

Figure 4-1. Converting a very large terrain dataset to tiled datasets.

Figure 4-2. The Terrain Tiles Layer attributes are automatically populated during the tiling process.

Background Data

Displaying the Terrain TIN (or GRID) provides detailed information on the river network and floodplain, but the display may prove agonizingly slow to refresh during digitizing, panning, or zooming. Creating background data such as contours or grid from the DTM will help you identify the study area and will redraw quickly to provide a good visualization for delineating the river network and locating cross sections.

To create a grid from a TIN model, select the 3D Analyst | Convert | TIN to Raster menu item. The dialog shown in Figure 4-3 allows you to select the Input TIN and other parameters. Typically, the default cell size will provide a good balance between accuracy and file size


4-6

when viewing the terrain model at a small scale (zoomed out). Press the OK button after providing a filename and location.

Processin e. A grid will be created e and added to the es for both the TIN an ed in on the rive t.

g time will be dependent on the TIN and cell sizby sampling the TIN based on the grid-cell siz

Map. You can then set the Scale Range propertid GRID, such that the TIN is displayed when zoomannel and the GRID is display when zoomed our ch

3. TIN to GRID conversion dialog. Figure 4-

ct the Surface Analysis | Analyst toolbar. the Input Surface,

To create contours from a DTM, seleContour menu item from the 3D Analyst or SpatialThe dialog shown in Figure 4-4 allows you to selectContour Interval, Output feature data set, and other parameters.

Figure 4-4. Contour setup dialog.


4-7

The contour interval selected should be based on the resolution of the terrain model. After setting the parameters, press the OK button.

Stream Centerline Layer

T nd reac enterline layer. The network is created on a reach by reach basis, starting from tthalweg. Each rea r Name and a Reach Name.

The Stream Centecross sections and tic in the HEC-RAS Geometric editor. It may also be used to define the main channel flow path.

e

nstream.

• Junctions are formed from the intersection of two (or more) rivers, ifferent River Name (River). A River name

represents one continuous flow path. For instance, the Mississippi e

llow you to enter a name for the new feature class – “River” is the default.

The status bar at the bottom of the ArcMap interface will provide information on the status of the contouring process. When completed, you will be asked if you wish to add the features to the current Map. Note: the contour layer is used for visualization only and is not usedduring the data extraction process.

he river a h network is represented by the Stream C

he upstream end and working downstream following the channel ch is comprised of a Rive

rline Layer is used for assigning river stations to to display as a schema

Rules! • The Stream Centerline must be created in the downstream

direction – each river reach line must start at the upstream end (the FromNode) and finish at the downstream end (the ToNode).

• Each river reach must have a unique combination of its River Nam(River) and Reach Name (Reach).

• All river reaches must be connected at junctions. Junctions are formed when the downstream endpoint (ToNode) of a reach coincides with the upstream endpoint (FromNode) of the next reach dow

each having a d

River has many reaches but is one river. Tributaries that enter thMississippi River, such as the Ohio River, have a new River name.

• Stream Centerlines should not intersect, except at confluences (junctions) where endpoints are coincident.

Creating the River Network

Select the RAS Geometry | Create RAS Layer | Stream Centerline menu item. The dialog shown in Figure 4-5 will a


4-8

Figure 4-5. Supply a name when creating a new feature class.

empty fields in the attribute table (as summarized in Table 4-2) will be created. The empty feature class will be added to the active Map.

rline fields.

Press OK and a new feature class with several

Table 4-2. Summary of Stream Cente

Field Description

HydroID Long Integer – unique feature identifier.

River String – River Name specified by user.

ode Short Integer – Identifies starting/upstream endpoint of reach.

Short Integer – Identifies ending/downstream endpoint of

length to FromNode.

Reach String – Reach Name specified by user.

FromN

ToNode reach.

ArcLength Float – Length of reach.

FromSta Float – Measurement at ToNode (normally 0.0).

ToSta Float – Measurement

You must be in Edit mode to create a river reach. To begin editing, e

geodatabase to edit, select the

select Start Editing from the Editor toolbar. After selecting th

(Sketch) tool. Use the mouse to use button to create the

rline in the downstream direction, using the left mouse click to add vertices. Double-click the

fter completing the river network, you must populate the River and

each fields with river reach names using the

digitize the stream centerline. Use the left mofirst point and continue creating the cente

mouse button to finish drawing the sketch. When you have completed digitizing the stream centerline features, save edits and stop editing the layer.

The pan and zoom tools are available from the Tools toolbar while editing. Simply choose a tool, use it and then reactivate the sketch tool to continue digitizing.

A

R (River ID) tool. fter activating the River ID tool, select a reach with the mouse A


4-9

pointer. Enter the River Name and Reach Name in the dialog provided (shown in Figure 4-6).

or River Name and Reach Name assignment. Figure 4-6. Dialog f

Junctions

J are fo n HEC-RAS, you may o ) at a flow c tionmust oincidat endpoints is to use the snapping method described below.

1. Start Ed terline feature class using Modify Feature as the Task.

2. Select the Editor | Snapping menu item and select the Stream Centerline feature class to have snapping at the endpoint.

unctions rmed at the confluence of three or more reaches. Inly have a new reach (and a junction

hange locabe c

. In order for a junction to be formed, reach endpoints ent. One method to ensure that junctions are formed

iting the Stream Cen


4-10

3. Select the Editor | Options menu item and set the SnappingTolerance on the General tab.

4. Activate the (Edit) tool.

5. Select an endpoint at the junction location.

6. Move the endpoints from the other reaches toward the junction location one at a time allowing the snapping and tolerance to snap the endpoints together.

Uniqueness

The river network must have unique reach names for each river. A river name is used for one river – one, connected flow line. Verify that

Stream

The Stream Centerline must be created in the downstream direction. o verify the orientation of the stream network, change the line

symbol to a line symbol with arrows.

If the line was created in the wrong direction, you can flip the line to oint downstream. While in edit mode, right-click on the feature and

select Flip from the context sensitive menu.

each river and each river reach is unique by opening the Centerline attribute table.

Directionality

T

p


4-11

Attributing the Stream Centerline Layer

Y fy Reach names for the Stream Centerline layer. The HydroID data will be completed by the ApFramework. The r ributthe Stream Cente ed in Table 4-3. The Elevations menand typically sho

Table 4-3. Stream Centerline completion menu items.

Menu Item

ou must speci the River and

emaining att es are completed by running GeoRAS menu items for rline as summariz

u item is OPTIONAL – the data is not used in HEC-RAS – uld NOT be run.

Description

Topology Populates the FromNode and ToNode fields.

Lengths/Stations Calculates the length for each river reach. Populates tFromSta and ToSta fields.

he

Elevations Extracts elevation data from the DTM and creates a 3D feature class. (Optional)

All Performs all tasks listed above in order.

Topology

The Topology menu item is used to verify that the Stream Centerline created a river network. Each reach endpoint (FromNode and ToNodeis given an integer ID. Reach endpoint

) s at a junction should each

have the same integer ID. If endpoints are not coincident between aches, the river stationing will not be consistently applied tions. You must check the values assigned to the

ions menu item calculates the length of each river mines the flow direction. This will be used to compute

sing

two river reto cross secFromNode and ToNode fields to verify the connectivity of theriver network – that junctions are formed by coincident reach endpoints!

Lengths/Stations

The Lengths/Statreach and deterthe river station for each cross section. Lengths and values for the FromSta and ToSta will be computed based on the units for the coordinate system (feet or meters).

FromSta and ToSta data may be overwritten. This may be done u

the (River Mile) tool or by computing a new value in the attribute table. Adjust the river stationing if you would like your study reach to start at a specific river station other than “0.0”.


4-12

Elevations

The Elevations menu item will convert the Stream Centerline 2D layer to a 3D layer. Elevation data for the stream centerline is not used in HEC-RAS, so this is an unnecessary step.

All

This menu option will run the Topology, Lengths/Stations, and Elevations menu items in sequence.

Cross-Sectional Cut Lines Layer

The location, position, and extent of cross sections are reprthe Cross-Sectional Cu er. Cut lines should be perpento the direction of flow; therefore, it may be necessary to “dog-lthe cut lines to form to this one-dimensional flow requiremen

While the cut lines represent the planar location of the cross sections, the station-elevation data are extracted along the cut line from the DTM.

esented by dicular

eg” t.

Rules! st be oriented from the left overbank to

the right overbank, when looking downstream.

f the DTM.

Creating Cross-Sectional Cut Lines

Select the RAS Geometry | Create RAS Layer | XS Cut Lines menu item. A dialog will allow you to enter a name for the new feature class – “XSCutlines” is the default.

A new feature class with several empty fields in the attribute table (as summarized in Table 4-4) will be created. The empty feature class will be added to the active Map.

t Line lay

con

• Cross-sectional cut lines mu

• Cut lines should be perpendicular to the direction of flow (considering the entire range of flow events).

• Cut lines should not intersect.

• Cut lines must cross the Stream Centerline exactly once.

• Cut lines may not extend beyond the extents o


4-13

Table 4-4. Summary of the XS Cut Lines fields.

Field Description


River String – Populated from the Stream Centerline layer.

Reach String – Populated from the Stream Centerline layer.

Station

iver station assigned from Stream Centerline layer.

LLength stream reach length for the left overbank m Flow Path Centerlines layer.

ChLength Fl stream reach length for the main channel calculated from Flow Path Centerlines layer.

RLength oat – Downstream reach length for the right overbank calculated from Flow Path Centerlines layer.

LeftBank Float – Percent along the cut line to left bank calculated from Bank Lines layer.

RightBank Float – Percent along the cut line to right bank calculated from Bank Lines layer.

Float – R

Float – Downcalculated fro

oat – Down

Fl

NodeName String – Cut line description specified by user.

You must be in edit mode to create a cross-sectional cut line. Selec

the

t

(Sketch) tool and use the mouse to digitize a cut line. Use thleft mouse button to create the first point and continue creating thcut line from the left overbank to the right overbank, using the left mouse click to add vertices. Cut lines should be created perpendicul

e e

ar to the direction of flow, intersect the stream centerline only once, and should not cross any other cut lines. Each cut line should cover the

extent of the floodplain and not extend beyond the extent of the terrain model.

u eted digitizing the cut line features, stop editing the feature

class. Verify that the cut lines were constructed from the left to right bank by adding an arrow symbol. The direction of the cut line may be flipped (while in edit mode) by right-clicking on the feature and selecting Flip from the context sensitive menu.

Previewing Cross Sections

Cross sections can be previewed using the

entire

Double-click the mouse button to finish drawing the sketch. When yohave compl

(XS Plot) tool. To preview a cross section, activate the XS Plot tool and then use the


4-14

mouse pointer to select the cut line of interest. GeoRAS will extract elevation information from the terrain model and display it in a

indow.

If the River, Reach, and Station data have been attributed to the

e

graphics w

feature it will be added to the title of the cross section plot, as shownin Figure 4-7. The x-axis will be labeled “Station” and corresponds to the distance from the left end of the cut line, while the y-axis will blabeled with “Elevation”. All units will be based on the units of the terrain model.

Figure 4-7. Sample cross section plot.

droID Manager. The remaining attributes are completed by running GeoRAS menu items for

Attributing the Cross-Sectional Cut Lines Layer

HydroID data will be completed by the Hy

the XS Cut Lines as summarized in Table 4-5.


4-15

Table 4-5. XS Cut Line completion menu items.

iption Menu Item Descr

River/Reach Populates the River and Reach fields based on the Stream Names Centerline layer.

Stationing Calculates the river station for each cut line based on the intersection with the Stream Centerline Layer. Populates the Station field.

Bank Stations Calculates the Left and Right bank positions as a percentage along the cut line using the Bank Lines layPopulates th

er. e LeftBank and RightBank fields.

lds.

Elevations Extracts elevation data from the DTM and creates a 3D feature class. The default name is “XSCutLines3D”.

Downstream Reach Lengths

Calculates the Left, Channel, and Right reach lengths based on the Flow Path Centerlines layer. Populates LLength, ChLength, and RLength fie


River/Reach Names

Each cut line is attributed with a River and Reach name based on the ust intersect the

nce

The

e will be computed if the Bank d RightBank fields are

ong the cut line to the bank e cut line and bank line. This

od for computing bank station

names in the Stream Centerline layer. Cut lines mStream Centerline layer exactly once.

Stationing

A river Station is calculated for each cut line based on the distafrom the most downstream point on the River. Calculations are basedon the FromSta and ToSta values in the Stream Centerline layer. calculated station is used to order cross sections when computing water surface profiles in HEC-RAS.

Bank Stations

The main channel banks of each cut linLines layer is provided. The LeftBank anpopulated with the percent distance alposition based on the intersection of thcomputation is optional. The methpositions is illustrated in Figure 4-8.


4-16

s and cut lines.

gth distance will be method for computing

gure 4-9.

Figure 4-8. Calculation of bank station locations from bank line

Downstream Reach Lengths

Downstream reach lengths will be computed for the Left overbank, main Channel, and Right overbank based on the length of the flow path lines in the Flow Path Centerlines layer. The distances are recorded in the LLength, ChLength, and RLength fields. If only the main Channel flow path exists, only the ChLencomputed. This computation is optional. The downstream distances is illustrated in Fi

0.65

0.71


4-17

igure 4-9. Calculation of downstream reach lengths from flow paths and cut lines.

Elevations

E are e section. The elevations are stored by converting the 2D cut line feature class to a 3D feature class GRID, elevations are extracted at the edge of each cell. If the DTM is a levation ).

All

This menu optio Stationing, Bank Stations, Downstream Reach Lengths, and Elevations menu items in sequence.

F

levations xtracted from the DTM for each cross

(default name “XSCutLines3D”). If the DTM is a

TIN, e s are extracted at the edge of each facet (triangle

n will run the River/Reach Names,

Right

Left

CChannel hannel


4-18

Bank Lines

The Bank Lines layer defines the main channel flow from flow in the overbanks. Bank stations will be assigned to each cross section based

cut lines. It is often e the data in HEC-RAS

ules! ach cut line.

• Bank lines may be broken (discontinuous).

• Orientation of the bank lines is not important (you may create the ups

• – crea required.

Creating the Ban

S S Ge item. A dialog wil ure class – “Banks” is the default.

A new feature class will be created and added to the active Map. The ded to the feature class is the HydroID field

d by the HydroID Manager as each feature is

You must be in edit mode to create the banks lines. Select the

Layer

on the intersection of the bank lines with themore efficient to skip this layer and completusing the Graphical Cross Section Editor tools.

R• Exactly two bank lines may intersect e

lines from

Optional

tream to downstream or downstream to upstream).

ting this layer is not

k Lines Layer

elect the RA ometry | Create RAS Layer | Bank Lines menul allow you to enter a name for the new feat

only field of interest adwhich will be populatecreated. Bank lines should be created on either side of the channel to differentiate the main conveyance channel from the overbank areas.

(Sketch) tool and use the mouse to digitize a bank line. Use the left

create the first point and continue creating the line, using the left mouse click to add vertices. Each bank line should only

e feature

mouse button to

intersect a cross-sectional cut line once.

Double-click the mouse button to finish drawing the line. When you have completed digitizing the cut line features, stop editing thclass.


4-19

Flow Path

The Flow Path Centerlines layer is used to identify the hydraulic flow , main channel, and right overbank by mass of flow in each region. Further, creating

the flow path centerline layer will assist you in properly laying out the ts

lculated for each cut line based on the distance between cut lines along the flow path centerlines for the left overbank, main channel, and right overbank.

ver.

• actly once.

• Flow path lines should not intersect.

.

am centerline for the main channel flow path (see Figure 4-10). Choose “Yes” to copy the stream centerline.

Centerlines Layer

path in the left overbankidentifying the center-of-

cross-sectional cut lines. If the Stream Centerline layer already exisyou have the option to copy the stream centerline for the flow path in the main channel. Flow paths are created in the direction of flow (upstream to downstream).

Downstream reach lengths are ca

Rules! • Flow path lines must point downstream (in the direction of flow).

• Each flow path line must be continuous for each Ri

Each flow path line must intersect a cut line ex

• Optional – creating this layer is not required

Creating the Flow Path Centerlines Layer

Select the RAS Geometry | Create RAS Layer | Flow Path Centerlines menu item. A dialog will allow you to enter a name for the new feature class – “Flowpaths” is the default. If the Stream Centerline layer already exists, you will be asked if you would like to use the stre

Figure 4-10. Copy stream centerline to flow path centerline.

A new feature class will be created and added to the active Map. The feature class will have the HydroID field and a LineType field. The


4-20

LineType field will designate whether the flow path line is for the “Channel”, “Left” overbank, or “Right” overbank.

main

Table 4-6. Summary of Flow Path Centerlines fields.

Field Description


LineType String – Populated using the A“Channel”, “Right” values desi

ssign LineType tool – “Left”, gnate the flow path.

You must be in edit mode to create the flow path lines. Select the ze a flow path line. Use the

nd continue creating the e flow path line

nd intersect a cut line

n you ature

verbank, ain “Channel”, or “Right” overbank. You can assign the LineType

(Sketch) tool and use the mouse to digitileft mouse button to create the first point aline, using the left mouse click to add vertices. Thmust be created in the downstream direction aexactly once.

Double-click the mouse button to finish drawing the sketch. Whehave completed digitizing the cut line features, stop editing the feclass.

Attributing the Flow Path Centerlines Layer

Each flow path line must be identified as being in the “Left” om

using the (Assign LineType) tool. Activate the LineType tool and use the mouse pointer to select a flow path. In the dialog that appears (see Fig lect the corresponding type of flow path. You must click on each flow path individually.

ure 4-11), se

ine type to each flow path centerlineFigure 4-11. Assign a l .

Bridges/Culverts Layer

The locations of river crossings are represented by the Bridge/Culvert layer. Cut lines for bridges and culverts are treated much the same as


4-21

for cross sections. Cut lines will bestation for the bridge or

used to identify the correct river culvert and will extract station-elevation data

for the top-of-road for the bridge deck from the DTM.

right overbank, when looking downstream.


line may not extend beyond the extents of the DTM.

Creating the Bridges/Culverts Layer

r | Bridges/Culverts menu item. A dialog will allow you to enter a name for the new

bute table (as summarized in Table 4-7) will be created. The empty feature class will

Rules! • Cut lines must be oriented from the left overbank to the

• A cut

• Optional – creating this layer is not required.

Select the RAS Geometry | Create RAS Laye

feature class – “Bridges” is the default.

A new feature class with several empty fields in the attri

be added to the active Map.

Table 4-7. Summary of Bridge/Culvert fields.

Field Description



Reach String – Populated from the Stream Centerline layer.

gned from Stream Centerline layer.

USDistance Float – User specified distance from upstream face of bridge

Station Float – River station assi

to next cross section upstream.

TopWidth Float – User specified width (in direction of flow) of the bridge deck.

NodeName String – Description of bridge specified by user.

You must be in edit mode to create a bridge/culvert cut line. Select

the (Sketch) tool and use the mouse to digitize a cut line. Use the left mouse button to create the first point and continue creating the cut line from the left overbank to the right overbank, using the left mouse click to add vertices.


4-22

Double-click the mouse button to finihave completed digitizing the cut line featclass. Enter the Top Width of the brcross section upstream. You need nobut HEC-RAS will require this information

Attributing the Bridges/Culverts Layer

HydroID data will be completed by the ApFattributes are completed by running GeoRAS Bridge/Culvert as summarized in Table 4-8

sh drawing the sketch. When you ures, stop editing the feature

idge deck and Distance to the next t complete this data in the GIS,

to perform a simulation.

ramework. The remaining menu items for the

.

Table 4-8. Bridge/Culvert completion menu items.

Menu Item Description

River/Reach Names

Populates the River and Reach fields based on the StrCenterline layer.

eam

Stationing Calculates the river station for each cut line basedintersection with the Stream Centerline Layer. Populates the Station field.

Elevations Extracts elevation data from the DTM and creates a 3D feature class.

on the

The default name is “Bridges3D”.

rder. All Performs all tasks listed above in o

River/Reach Names

Each bridge is a River and Reach name based on the names in the Stream Centerline layer. Cut lines must intersect the Stream Centerli

Stationing

A riv ation is calcufrom the most d ed on the FromSta nterline layer. The calculated Statio nodes when compu g wate

Elevations

Elevations are extracted from the DTM for each bridge. The elevations are stored by converting the 2D bridge/culvert feature class to a 3D feature class (default name “Bridges3D”).

ttributed with a

ne layer exactly once.

er st lated for each cut line based on the distance ownstream point on the River. Calculations are bas and ToSta values in the Stream Cen is used to order cross sectionr surface profiles in HEC-RAS. tin


4-23

All

This menu option will run the River/Reach Names, Stationing, and

Ineffective

s portions of the floodplain that do not actively convey flow. This layer is created in areas of zero velocity such as the dead-water zones upstream and downstream of

nd culverts. The position of ineffective areas will be extracted

constructed to form “blocks”.

ual and RD-42 (HEC, 1995) for guidance on flow transitions at bridges.


Layer | Ineffective Flow Areas menu item. A dialog will allow you to enter a name for the new

d and added to the active Map. The nly field of interest added to the feature class is the HydroID field

ramework when each feature is created.

You m be in edi the

Elevations menu items in sequence.

Flow Areas Layer

The Ineffective Flow Areas layer identifie

bridges abased on the intersection of the Ineffective Flow Areas layer and the Cross-Sectional Cut Lines layer.

Rules! • Ineffective polygons should be

• Consult the HEC-RAS Hydraulic Reference Man

Creating the Ineffective Flow Areas Layer

Select the RAS Geometry | Create RAS

feature class – “IneffectiveAreas” is the default.

A new feature class will be createowhich will be populated by the ApF

ust t mode to create a ineffective area. Select ( tool a ble-click the mouse butto h. When you have completed digiti , stop editing the feature class.

,

Sketch) nd use the mouse to digitize each area. Doun to finish drawing the sketczing the polygon features

Ineffective Flow Area Attributes

Ineffective flow area positions and elevations are extracted by selecting the RAS Geometry | Ineffective Flow Areas | Positions menu item. The dialog shown in Figure 4-12 will allow you to choosethe Ineffective Flow Areas layer, Cross-Sectional Cut Lines layer, DTMand provide a name for the table that will hold the ineffective positions


4-24

(“IneffectivePostions” is default). You can also specify to “keep current user elevations” to prevent overwriting previously stored data.

Figure 4-12. Ineffective flow areas data extraction dialog.

Ineffective flow area data are extracted based on the intersection of the cut lines and ineffective area and is written to the IneffectivePositions table. The beginning and ending position of intersection between the ineffective flow area and the cut line is

levation from the DTM. The used as a “trigger” elevation

Field Description

calculated as well as the corresponding eelevation extracted from the DTM will bein HEC-RAS for turning off the ineffective areas. If the user specifies a UserElev it will be used, otherwise the larger of the two elevations computed for the beginning and ending position will be used. The IneffectivePosition table fields are summarized in Table 4-9.

Table 4-9. Summary of IneffectivePositions table fields.

XS2DID Long – Integer corresponding to the cross-sectiline’s HydroID.

onal cut

IA2DID Long – Integer corresponding to the ineffectiareas HydroID.

BegFrac Float – Fraction of the distance along the cut libeginning of the ineffective area.

EndFrac Float – Fraction of the distance along the cut libeginning of the ineffective area.

BegElev Float – Elevation at the BegFrac.

ve flow

ne to the

ne to the

EndElev Float – Elevation at the EndFrac.

UserElev Float – User specified Elevation


4-25

Blocked O

The Blocked Obstructions layer identifies portions of the floodplain that permanently remove flow area from the cross section. This layer is

oachment. The position of blocked d on the intersection of the Blocked

er

AS Layer | Blocked llow you to enter a name for

edObs” is the default.

and added to the active Map. The e feature class is the HydroID field

ork when each feature is

a blocked obstruction area. Select

bstructions Layer

created in areas of floodplain encrobstructions will be extracted baseObstructions layer and the Cross-Sectional Cut Lines layer.

Rules! • Blocked obstruction polygons should be constructed to form

“blocks”.


Creating the Blocked Obstructions Lay

Select the RAS Geometry | Create RObstructions menu item. A dialog will athe new feature class – “Block

A new feature class will be created only field of interest added to thwhich will be populated by the ApFramewcreated.

You must be in edit mode to create

the (Sketch) tool and use the moDouble-click the mouse button to finihave completed digitizing the polygon fefeature class.

use to digitize each area. sh drawing the sketch. When you

atures, stop editing the

g

specify to “keep current user elevations” to prevent overwriting previously stored data.

Blocked Obstruction Attributes

Blocked obstruction extents and elevations are extracted by selectinthe RAS Geometry | Blocked Obstructions | Positions menu item.The dialog shown in Figure 4-13 will allow you to choose the Blocked Obstructions layer, Cross-Sectional Cut Lines layer, DTM, and provide a name for the table that will hold the blocked positions (“BlockedPositions” is default). You can also


4-26

Figure 4-13. Blocked obstruction data extraction dialog.

Blocked obstruction data are extracted based on the interscut lines and blocked area polygons and is written to theBlockedPositions table. The beginning and endiintersection between the blocked area and the cut linwell as the corresponding elevation from the DTM. The extracted from the DTM will be used as the top-of-obstru

ection of the

ng position of the e is calculated as

elevation tion

UserElev it will be used, puted for the beginning

nd ending position will be used. The BlockedPosition table fields are

T 10. Summary of fiel edPositions table.

c elevation in HEC-RAS. If the user specifies a

otherwise the larger of the two elevations comasummarized in Table 4-10.

able 4- ds in the Block

Field Description

XS2DID Long – Integer corresponding to the cross-sectional cut line’s HydroID.

BO2DID Long – Integer corresponding to the blocked obstruction HydroID.

oat – Fraction of the distance along the cut line to the eginning of the blocked obstruction.

EndFrac Float – Fraction of the distance along the cut line to the

.

BegFrac Flb

beginning of the blocked obstruction.

BegElev Float – Elevation at the BegFrac.

EndElev Float – Elevation at the EndFrac

UserElev Float – User specified Elevation.


4-27

Land Use L

A Land Use layer may be used to estimate Manning’s n values along line. The land use data set must be a polygon layer and have

n values (N_Value for instance). If an N_Value

ernatively, you may add e class using standard

the active Map.

.

ayer

each cuta field to reference for field does not exist, GeoRAS provides tools for creating a summarytable of n values based on a land use field. Altthe N_Value field to an existing polygon featurArcGIS functionality for GeoRAS to use.

Rules! • The land use data set must be a 2D polygon data set that

encompasses the entire set of cut lines.

• Multipart polygons are not supported.

• The land use layer must have (or reference) an N_Value field.

• Polygons must share an edge.


Creating the Land Use Layer

Select the RAS Geometry | Create RAS Layer | Landuse Areas menu item. A dialog will allow you to enter a name for the new feature class – “LandUse” is the default.

A new feature class with empty fields in the attribute table (as summarized in Table 4-11) will be created. The empty feature class will be added to

Table 4-11. Summary of Land Use fields

Field Description

LUCode String – Short description of land use type.

N_Value Float – Manning’s n value.

You must be in edit mode to create a land use area. Select the (Sketch) tool and use the mouse to digitize each area. One method is to begin by digitizing a bounding area around the project area. This ensures that each cross section is contained by a viable polygon.

Continue by digitizing polygons around specific land use classes. Left-click to add a vertex point, double-click to end a sketch. After each polygon is digitized, select Clip from the Editor toolbar. In the Clip properties dialog (shown in Figure 4-14), choose a Buffer Distance of


4-28

“0.0” and to Discard the intersecting area. This wnon-overlapping polygon.

ill create a unique,

ption in the LUCode field. he description should be standardized – you will use it again for a

n value in the N_Value LUCode data is not required.

W ing the stream centerline features, s g the

C the L

I lue d n use GeoRAS to crea mary table to which you can add n values. Select the RAS Geometery | Manning’s n Values | Create LU-

Figure 4-14. Clip land use polygons to create unique, non-overlapping features.

After completing the polygon, enter a descriTsimilar land use area. You may also enter the field. If you enter the N_Value data, the

hen you have completed digitiztop editin layer.

reating and Use Layer Table

f the N_Va ata is not present in the Land Use layer, you cate a sum

Manning Table. This will invoke the dialog shown in Figure 4-15 which allows you to specify the Land Use layer, the Land Use description field, and the name of the Summary Manning Table to create.

Figure 4-15. Specify the Land Use classification field to summarize n value data.

the types of land use t-e

A new table will be created that summarizes specified in the LUCode field and is added to the ArcMap document. Change the ArcMap Table Of Contents tab to the Source Tab. Righclick on the LUManning table to access the table. The table will hav


4-29

a summary of the land use descriptions and have an empty N_Valudata field. Enter n value data into the table that corresponds toland use description.

e the

Land Use layer or the e with the Manning’s n

y | Manning’s n dialog shown in Figure

put/output data. You value field (N_Value) from

Values in Land use table by choosing the

Manning’s n Value Attributes

After completing the n value data entry in theLUManning table, you can attribute each cut linvalue information. Select the RAS GeometerValues | Extract N Values menu item. The4-16 is invoked and allows you to specify the inhave the choice of using the Manning’s n the Land Use layer by choosing the “ManningLayer” option or the values in the LUManning“Table of Manning Values” option.

Figure 4-16. Manning's n value extraction dialog.

Specify the name of the output table (“Manning” is default) and press cross-sectional cut Manning output

e HydroId for the cut ding location on the

land use area polygon summary of the fields in

OK. Manning’s n values will be extracted for eachline, as shown in Figure 4-17, and reported to the table. The output table will be populated with thline and the Manning’s n value with the corresponcut line. The location of the beginning of each is reported as a fraction along the cut line. A the Manning table is provided in Table 4-12.


4-30

Figure 4-17. Calculation of Manning's n value positions.

Table 4-12. Summary of Manning table fields for extraction of n value data.

Field Description

XS2DID Long – Integer corresponding to the cross-sectional cut line’s HydroID

Fraction Float – Fraction of the distance along the cut line tbeginning of the land use type

o the

N_Value Float – Manning’s n value

Levee Alig

er is but should also be

S only supports one levee per bank er cross section – one levee in the left overbank, one in the right

he levee alignment tools are intended to work with both existing and roposed levee features. Existing levee features are those that have

nment Layer

The Levee Alignment layer is used to define a linear feature that contains the lateral flow of water in the floodplain. The levee layintended to be used to represent leveed systems, used to indicate high ground that contains water such as roads or ridges that connect multiple cross sections.

Note that at Version 4.0, HEC-RApoverbank.

Tp


4-31

been incorporated in the terrain model, while proposed features are those that do not have profile information in the terrain model.

R• ingle lev .

• levee p


Creating the L

S RASmenu item. A dialog will allow you to enter a name for the new feature class –

You must be in edit mode to create the levee lines. Select the

ules! A s ee line may intersect a cross section exactly once

One er bank (HEC-RAS limitation).

evee Alignment Layer

elect the Geometry | Create RAS Layer | Levee Alignment

“Levees” is the default.

A new feature class will be created and added to the active Map. The only field of interest added to the feature class is the HydroID field which will populated by the ApFramework when each feature is created.

Double-click the mouse button to finish drawing the sketch. When you have completed digitizing the cut line features, stop editing the feature

rporated in the DTM, n enter profile data using the

(Sketch) tool and use the mouse to digitize a levee line. Use the left mouse button to create the first point and continue creating the line, using the left mouse click to add vertices. Each levee line should only intersect a cross-sectional cut line once.

class.

Entering Levee Elevation Data

If the levee profile information has not been incoyou ca (Levee Elevation) tool. When

ialog shown in Figure 4-18 will be invoked allowing you to choose the Levee Alignment layer, the D d th able to add station-elevation points (“LeveePoints” is default).

the Levee Elevation tool is activated, the d

TM layer, an e name of a t


4-32

Figure 4-18. LeveePoints table input dialog.

The LeveePoints table will be created and added to ArcMap. Data will be atttributed to the fields shown in Table 4-13 as you enter data using the Levee Elevation tool.

Table 4-13. Summary of LeveePoints table fields.

Field Description

LeveeID Long – Integer corresponding to the levee line’s HydroID in the Levee Alignment layer.

Station Float – Distance along the levee line to Elevation.

Elevation Float – User defined elevation at the corresponding Station.

Using the mouse psnapped to the lev

ointer, click on a levee line. The pointer will be ee line and graphic will be drawn to the screen. A

dialog (shown in Figure 4-19) will then report to you the elevation of e the DTM at that point and await entry for the new elevation. Th

specified location, elevation, and levee ID will be entered into the LeveePoints table.

9. Levee elevations data entry dialog.

P ior to assigning the levee position and elevation attributes to the Cross-Sectional Cut Line layer, the Levee Alignment layer must be converted to a 3D feature class. This is performed by selecting the

Figure 4-1

Completing the Levee Alignment Layer

r


4-33

RAS Geometry | Levees | Profile Completion menu item. The dialog shown in Figure 4-20 will allow you to choose the Levee

e

Alignment layer and name of the Levee Profiles (3D) layer. You are also provided the option to use the LeveePoints table or to use thterrain model for the elevations along the levee line.

Figure 4-20. The Levee Alignment is converted to a 3D feature class prior to attributing t

Levee Attributes

The intersection of the Levee Profiles layer and Cross-Sectional Cut

line. Levee positions are extracted by selecting the RAS Geometry |

sitions” is default). The LeveePositions table will be created

he cut lines.

Lines layer will extract the levee position and elevation at each cut

Levees | Positions menu item. The dialog shown in Figure 4-21 will allow you to select the Levee Profiles layer, XS Cut Lines layer, DTM,and enter the name for the levee position/elevation data (“LeveePowith several fields (summarize in Table 4-14) and data will be populated based on the intersection of each levee line and each cut line.

gure 4-21. Levee position/elevation data extraction dialog. Fi


4-34

Table 4-14. Summary of LeveePositions table fields.

Field Description

Lev2DID LoHy t layer.

ng – Integer corresponding to the levee line’s droID in the Levee Alignmen

XS2DID Loin

Fraction Float – Position along the cut line as a fraction of the to

GrndElev Float – Elevation of the DTM at the levee position.

Elevation Float – Top-of levee Elevation at the levee position.

ng – Integer corresponding to the cut line’s HydroID the Cross-Sectional Cut Line layer.

tal cut line length.

Inline Struc

Structu

not extend beyond the extents of the DTM.

tures Layer

The locations of inline weirs (and dams) are represented by the Inline res layer. Cut lines for inline structures are treated similar to

erts. Cut lines will be used to identify the river station for ructure and will extract station-elevation data for the top-

bridges/culvthe inline stof-weir profile from the DTM.

Rules! • Cut lines must be pointed from the left overbank to the right

overbank, when looking downstream.


• Cut lines may


Creating the Inline Structures Layer

Select the RAS Geometry | Create RAS Layer | Inline Structures menu it ow you to enter a name for the new feature class – “InlineStructures” is the default.

A new feature class with several empty fields in the attribute table (as summarized in Table 4-15) will be created. The empty feature class will be added to the active Map.

em. A dialog will all


4-35

Table 4-15. Summary of Inline Structure fields.

Field Description



String – Populated from the Stream Centerline layer.

igned from Stream Centerline layer.

USDistance Float – User specified distance from upstream face of weir to next cross section upstream.

Float – User specified width (in direction of flow) of the weir.

Reach

Station Float – River station ass

TopWidth

NodeName String – Description of structure specified by user.

You must be in edit mode to create an inline structure cut line. Select

the (Sketch) tool and use the mouse to digitize a cut line. Use the left mouse button to create the first point and continue creating the

m the left overbank to the right overbank, using the left lick to add vertices.

Double-click the mouse button to finish drawing the sketch. When you he

feature class. Enter the top width of the weir and distance to the next cross section upstream. You need not complete this data in the GIS,

to perform a simulation.

HydroID data will be completed by the ApFramework. The remaining r the

able 4-16. Inline Structure completion menu items.


cut line fromouse c

have completed digitizing the inline structure features, stop editing t

but HEC-RAS will require this information

Attributing the Inline Structures Layer

attributes are completed by running the GeoRAS menu items foInline Structures as summarized in Table 4-16.

T

River/Reach Populates the River and Reach fields based on the Stream Names Centerline layer.

Stationing n the am Centerline Layer. Populates

the Station field.

Elevations om the DTM and creates a 3D feature class. The default name is “InlineStructures3D”.

All ve in order.

Calculates the river station for each cut line based ointersection with the Stre

Extracts elevation data fr

Performs all tasks listed abo


4-36

River/Reach Names

Each structure is attributed with a River and Reach name based on thenames in the Stream Centerline layer. Cut lines must intersect the Stream Centerline layer exactly once.

. Calculations are based on the FromSta and ToSta values in the Stream Centerline layer. The calculated Station is used to order computation nodes when computing

levations are extracted from the DTM for each weir. The elevations e feature class to a 3D

ures3D”).

All

T nu option will run the River/Reach Names, Stationing, and E u it

Lateral Structures Layer

The locations of lateral structures to represent weirs and gated s tures are re yer. Cut lines for lateral structures are treated similar to inline structures. Cut lines

fy the correct river station for the lateral structure tion-elevation data for the weir profile from the

res are ill

rea.

Rules!

Stationing

A river station is calculated for each cut line based on the distance from the most downstream point on the River

water surface profiles in HEC-RAS.

Elevations

Eare stored by converting the 2D inline structurfeature class (default name “InlineStruct

his melevations men ems in sequence.

truc presented by the Lateral Structures la

will be used to identiand will extract staDTM.

Lateral structures should be constructed parallel to the main river and located at the end of cross-sectional cut lines. Lateral structuused in areas where flow is expected to leave the main river and spover a weir into another river or storage a

• Cut lines must be pointed in the downstream direction.

• Cut lines may not extend beyond the extents of the DTM.



4-37

Creating the Lateral Structures Layer

Select the RAS Geometry | Create RAS Layer | Lateral Structures new

tribute table (as feature class

menu item. A dialog will allow you to enter a name for thefeature class – “LasteralStructures” is the default.

A new feature class with several empty fields in the atsummarized in Table 4-17) will be created. The emptywill be added to the active Map.

Table 4-17. Summary of Lateral Structure fields.

Field Description


River String – Populated from the Stream Centerl

Reach String – Populated from the Stream Centerl

Station Float – River station assigned from Stream Centerl

ine layer.

ine layer.

ine layer.

Float – User specified distance from upstream end of weir to next cross section upstream.

USDistance

TopWidth Float – User specified width of the weir deck.

NodeName String – Description of weir specified by user.

You must be in edit mode to create a lateral structure cut line. Selec

the

t

(Sketch) tool and use the mouse to digitize a cut line. Use thleft mouse button to create the first point and continue creating the cut line in the downstream direction, using the left mouse click to add vertices.

e

ouble-click the mouse button to finish drawing the sketch. When you have completed digitizing the lateral structure features, stop editing the feature class. Enter the Top Width of the weir and Distance to the next cross section upstream. You need not complete this data in the GIS, but HEC-RAS will require this information to perform a simulation.

Attributing the Lateral Structures Layer

HydroID data will be completed by the ApFramework. The remaining attributes are completed by running GeoRAS menu items for the Lateral Structures as summarized in Table 4-18.

D


4-38

Table 4-18. Lateral Structure completion menu items.


River/Reach Names

Populates the River and Reach fields frStream Centerline feature.

om the closest

Stationing Calculates the river station for each lateral sbased on the upstream end of the weir Stream Centerline feature. Populates the

Elevations Extracts elevation data from the DTM and creates a feature class. The default name is “LateralSt


tructure and the closest

Station field.

3D ructures3D”.

River/Reach Names

Each structure is attributed with a River and Reach name names in the Stream Centerline layer. The lateral structuthe nearest river reach.

Stationing

A river station is calculated for each lateral structure based on

based on the re looks for

the

layer. The calculated Station is based on the shortest distance to the onal

sed to determine ounding cross section nodes when computing water surface profiles in

distance from the most downstream point on the River. Calculations are based on the FromSta and ToSta values in the Stream Centerline

most upstream end of the lateral structure feature that is orthogto the stream centerline, as shown in Figure 4-22. Verify the computed river station! The station will be ubHEC-RAS.

Figure 4-22. Calculation of river station for a lateral structure

Lateral Structure


4-39

Elevations

Elevations are extracted from the DTM for each weir. The elevations are stored by converting the 2D lateral structure feature class to a 3D

Stationing, and

Storage Areas Lay

Storage areas are used to model floodplain detention storage where simulated water surface will be horizontal. Storage areas are not

ed in the cross-sectional geometry. Typically, a storage area is

Rules! ithin the bounds of the DTM.

s.

Creating the Storage Areas Layer

e RAS Geometry | Create RAS Layer | Storage Areas A dialog will allow you to enter a name for the new

feature class (default name “LateralStructures3D”).

All

This menu option will run the River/Reach Names,Elevations menu items in sequence.

er

the reflectconnected to a series of cross sections using a lateral structure.

• Storage areas must be contained w

• Storage areas should not overlap one another or cross section

Select thmenu item. feature class – “StorageAreas” is the default.

A new feature class with empty fields in the attribute table (as summarized in Table 4-19) will be created. The empty feature class will be added to the active Map.

Table 4-19. Summary of Storage Area fields.

Field Description


MaxElev Float – Maximum elevation found from the DTM withinthe storage area boundary.

MinElev Float – Minimum elevati

on found from the DTM within the storage area boundary.

UserElev Float – User specified maximum elevation for computing elevation-volume relationship.


4-40

You must be in edit mode to create a storage area. Select the ch area. Digitize

polygons around specific areas that will store flood waters. Left-click t a vertex click to end a sketch.

S reas s -sectional cut lines. This is important for proper floodplain mapping as the area with the storage are evation. Storage areas t y a storage area connection in HEC-RAS should share

A g th

H a w aining attributes are completed by running GeoRAS menu items for the

(Sketch) tool and use the mouse to digitize ea

o add point, double-

torage a hould be created at the ends of cross

a will be given one, continuous water surface elhat will be connected b

a common edge.

ttributin e Lateral Structures Layer

ydroID dat ill be completed by the ApFramework. The rem

Storage Areas as summarized in Table 4-20.

Table 4-20. Storage Area completion menu items.


Elevation Populates the MaxElev and MinElev from the DTM. Range

Elevation –Volume Data

Calculates elevation-voluthe minimum elevation to

me curve for the storage area from the maximum elevation. If the

UserElev is specified, it is used as the maximum elevation.

Extraction ta is not used in

HEC-RAS and is not required. Terrain Point Extracts point data from the DTM. This da


Elevation Range

The Elevation Range menu item will search the terrain model for the l ghe ithin the storage area. The MinElev and MaxElev ill be popue ev tions a.

Elevation-Volum

E ation-volume dat f elevations. The elevation specified in the UserElev field will be used to override the maximum elevation computed by GeoRAS if the “Apply User Elevation” option on the elevation-volume extraction dialog, shown in Figure 4-23, is checked.

owest and hi st elevation w fields w

levations will bolume rela

lated with this data. The range of used as the bounds for computing the elevation-hip for the storage are

e Data

lev a will be extracted over the range o


4-41

The elevation-volume data is computed from the DTM and stored in a table specified by the user (“ElevVol” is default) (see Figure 4-23).

Figure 4-23. Specify the data input layers and output table for elevation-volume calculations.

e the incrementing method. Choosing the minimum slice density extracts volume information on an even interval

the of the elevation range). Figure 4-24 illustrates the impact of

the slice density on data extraction.

Volume calculations are performed based on incremental elevations (10 slice increments are used by default) starting at the minimumelevation and going up to the maximum elevation. The “Slice Density”option allows you to choos

starting at the MinElev and going up to the MaxElev. The maximum slice density will extract more volume information at elevations near the MinElev (with 80% of the volume information extracted within first 50%


4-42

Figure 4-24. The Slice Density option for Storage Areas allows for more detailed volume information to be extracted near the minimum elevation.

The ElevVol table will be created to store the elevation-volume relationship for each storage area. The fields populated by the data calculations are summarized in Table 4-21.

Table 4-21. Summary of Storage Area fields.

Field Description

SAID Long – Integer corresponding to the storage area’s HydroID in the Storage Area layer.

Elevation Float – Elevation of a horizontal surface within the storage area.

Volume Float – Volume between the elevation and the DTM (cubic units).

Area Float – Area of horizontal surface at the elevation.

Terrain Point Extraction

The terrain points within the storage area will be extracted and saved to a point feature class. The dialog shown in Figure 4-25 allows you to


4-43

specify the Storage Area layer, DTM, and point feature class to be created. HEC-RAS does not currently utilize the point data; therefore, this step is not necessary.

Figure 4-25. Specify an output feature class prior to extracting terrain point data.

All

This menu option will run the Elevation Range, Elevation-Volume Dand Terrain Point Extraction menu items in sequence.

Storage Area Connections Layer

ata,

ween storage odeled as a weir with

hydraulic structures in HEC-RAS.

nnection, there is exactly one upstream storage area and one downstream storage area.

Creating the Storage Area Connections Layer

Select the RAS Geometry | Create RAS Layer | SA Connections menu item. A dialog will allow you to enter a name for the new feature class – “SAConnections” is the default.

A new feature class with empty fields in the attribute table (as summarized in Table 4-22) will be created. The empty feature class will be added to the active Map.

Storage area connections are used to pass flow betareas. The storage area connection may be m

Rules! • Storage area connections should be oriented from left to right

when looking in the downstream direction.

• For each co


4-44

Table 4-22. Summary of Storage Area Connections fields.

Field Description


USSA Integer – corresponds to SAID (Storage Area ID) of upstream storage area.

DSSA Integer – corresponds to SAID (Storage Area ID) of downstream storage area.

TopWidth Float – User specified width of the weir.

NodeName String – Description of connection specified by user.

You must be in edit mode to create a storage area connection. Select

the (Sketch) tool and use the mouse to digitize each area. Digitize the location of the high ground separating two storage areas. Use the left mouse button to create the first point and continue creating the cut line from the left to the right, using the left mouse

Double-click the mouse button to finish drawing the sketch. When you

r

e remaining menu items for the

click to add vertices.

have completed digitizing the connections, stop editing the feature class. Enter the top width of the weir.

Attributing the Storage Area Connections Laye

HydroID data will be completed automatically. Thattributes are completed by running GeoRAS Storage Areas as summarized in Table 4-23.

Table 4-23. Storage Area completion menu items.


Assign Nearest SA

Calculates the nearest two storage areas. Populates the USSA and DSSA fields.

Elevations Extracts elevation data from the DTM and creates a 3D feature class. The default name is “SAConnections3D”.



4-45

Assign Nearest SA

Identifies the nearest two storage areas to the connection and populates the USSA and DSSA fields with the SAID from the storageareas. You must verify the computed storage areas are correct!

Elevations

ns o a 3D feature class (default name “SAConnections3D”).

his menu option will run the Assign Nearest SA and Elevations menu

Layer Setup

HEC-GeoRAS will keep track of the feature classes generated, data layers used for extracting attribute information, and the tables that hold extracted data. However, the Layer Setup will allow you to specify data you wish to write to the RAS GIS Import File by choosing which RAS Layers to use.

Select the RAS Geometry | Layer Setup menu item to access the Layer Setup window. Note that there are four tabs for specifying data: Required Surface, Required Layers, Optional Layers, and Optional Tables.

Required Terrain Surface

The Required Surface tab shown in Figure 4-26 allows you to specify which terrain model you wish to use for extracting elevation data. When you convert the Cross-Sectional Cut Lines (2D) feature class to a 3D feature class you will be provided a dialog to choose the terrain model. If you want to specify a different terrain model you can through the Layer Setup.

Elevations are extracted from the DTM for each connection. The elevations are stored by converting the 2D storage area connectiofeature class t

All

Titems in sequence.


4-46

Figure 4-26. A terrain model is required for use with GeoRAS.

Required Layers

GeoRAS requires the Stream Centerline (2D) layer, the Cross-Sectional Cut Lines (2D) layer, and the Cross Sections (3D) layer. You can specify which layers will be used to generate the RAS GIS Import File in the Layer Setup window on the Required Layer tab shown in Figure 4-27.

Figure 4-27. Required layers for creating the RAS GIS Import File.


4-47

Optional Layers

Optional Layers are used in GeoRAS to extract additional information. They are not required. Geospatial information and elevation data from

xport File. selected 3D feature classes will be written to the RAS GIS EOptional data layers are shown in Figure 4-28.

rted by GeoRAS.

Data tables selected on the Optional Tables tab, shown in Figure 4-29,

Figure 4-28. Optional data layers suppo

Optional Tables

will be written to the RAS GIS Import File. Most data tables are linkedto an associated 2D feature class which holds the geospatial shape information.


4-48

-29. Optional data tables used in GeoRAS.

Generating

Figure 4

the RAS GIS Import File

To generate the RAS GIS Import File, select the RAS Geometry | Extract GIS Data menu item. The dialog shown in Figure 4-30 will be displayed and allow you to pick a file location and file name.

Figure 4-30. Export GIS data dialog.

An ASCII file with the RASExport.sdf file extension will be createthe designated location. An intermediate XML file will also be extracted. At this time, HEC-RAS will only import the SDF filethe SDF and XML formats are fluid and may change as new features are added to the GeoRAS software.

The RAS GIS Import File has multiple sections. The first sectionHeader section. HEC-RAS only uses the “UNITS” parameter of thheader when importing data, to assist you in conversions when importing the data. The Stream Network section of the import fdefine the river network by River and Reach name and the geospatial portion (x, y points) will be used to create the river schematic. Th

d in

. Both

is the e

ile will

e


4-49

other required section in the import file is the Cross Sections section. The cross-sectional data is exported based on the Cross-Sectional

positions and elevations may also be written to the import file.

line

a

Profiles (3D) feature class. River and reach names, river station, cutline information, and station-elevation data will be specified. Other properties such as main channel bank stations, downstream reach lengths, ineffective flow areas, blocked obstructions, Manning’s n values, levee

Other structure data may be written out for Bridges/Culverts, InStructures, Lateral Structures, Storage Areas, and Storage Area Connections.

For a more detailed discussion of the spatial data format for GIS datexchange with HEC-RAS, please refer to Appendix B.

Chapter 5 GIS Data Exchange with HEC-RAS

5-1

C H A P T E

GIS Data Exchange with HEC-RAS

H has the he spatial data form ata gen er h odeRAS results can

T ll IS data, how to complete the hydraulic model for simulation, and export results t in

Contents • Importing GIS Data to HEC-RAS

• Completing t

• Completing t

• Exporting HEC-RAS Results

Importing GIS Data to H

To import GIS data, select the File | Import Geometry Data | GIS

R 5

EC-RAS capability to import geospatial data that follows tat discussed in Appendix B. Importing d

erated from GIS layydraulics m

ers, however, will not create a complete rivl. After completing the river hydraulics model, HEC-be exported for processing by GeoRAS.

his chapter wi discuss the methods available for importing G

o the GIS for undation mapping.

he Geometric Data

he Flow Data and Boundary Conditions

EC-RAS

Format menu item from the Geometric Data editor in HEC-RAS, as shown in Figure 5-1.


5-2

Figure 5-1. The GIS data import option on the HEC-RAS Geometric Data editor.

Intro

The Import Options window will guide you through the process of importing all or part of the GIS import file. The initial tab of the Import Options dialog is the Intro tab, shown in Figure 5-2. HEC-RAS

TS” tag. Based on the ll be offered the option to import

the data in the current unit system or to convert the data from one

will read the import file and look for a “UNIvalue associated with the tag, you wi

unit system to another. If no unit system is found in the GIS file the import dialog will default to your current RAS project units.

Figure 5-2. Unit system conversion is an import option in HEC-RAS.


5-3

River Reach Stream Lines

The next tab on the import options is the River Reach Stream Li(see Figure 5-3). This set of options allows you to specify whichreaches to import, how to import the data, and what to name the riand reach. Import options for the river and reaches are summarized in Table 5-1.

nes river

ver

Figure 5-3. River and reach import options.

Table 5-1. Summary of River Reach Import option fields.

Column Description

Import As River

The name of the River once it is imported to HEC-RAS.

Import As The name of thReach

e Reach once it is imported to HEC-RAS.

river reach exists in the HEC-s new.

g data, append upstream, or append downstream.

Import Status Identifies whether theRAS geometry file or i

Import Stream Lines

Checkbox to choose what river reaches to import. Use the spacebar to toggle the checkbox. All rows can be selected by clicking on the column header.

Merge Mode The river reach can replace existin


5-4

Cross Section and IB Nodes

The next tab on the Import Options window allows you to import cross sections and internal boundaries (bridges/culverts, lateral structures, and inline structures). The Cross Sections and IB Nodes screen options are shown in Figure 5-4.

be

Figure 5-4. Cross section and internal boundary import options.

There are several options for importing cross-sectional data. You must first specify the “Import River” and “Import Reach” upon which the cross sections reside. The import dialog will inform you what river and reach name the data will import to (Import As) in the HEC-RAS geometry. (The Import As information was specified on the River Reach Stream Lines tab). You can filter the data based on the node type (cross section, bridge/culvert, inline structure, lateral structure).You then specify the cross sections to import and the specific property to import.

Only those cross-sectional properties available in the import file willmarked as available for import. Properties selected will be imported for each cross section specified during the import process. The properties import option will allow you to update individual pieces of data (such as bank station data) without modifying the other data already specified in HEC-RAS.


5-5

The cross sections that will be imported and how they will be imported are specified in the import table. Import table options are summarized

ion and IB Nodes Import option fields.

in Table 5-2.

Table 5-2. Summary of Cross Sect

Column Description

Import File River

The name of the River in the import file. Refer to the associated Import As field to see the name of the river that the cross section will be imported into.

Import File Reach

The name of the Reach in the import File. Refer to the associated Import As field to see the name of the reach that the cross section will be imported into.

Import File RS The name of the River Station in the import file.

Import As RS The name of the River Station the cross section will be imported into. This data may be user-specified and changed using the provided tools. The “Reset” button will replace the river station data with the dimport file.

ata in the

Import Status The Import Status will be “New” or “Exists”. New will he data. Exists will update

th the properties

e

add the cross section to t(replace) the existing data wispecified.

Import Data Checkbox to choose what river stations to import. Usthe spacebar to toggle the checkbox. All rows can be selected by clicking on the column header. You can also use the buttons provided to select all of the New cross sections (Check New) or those that Exist (Check Existing).

There are also several tools provided to change the river station name. River station identifiers are the link between the GeoRAS generated data and the HEC-RAS data. Cross-sectional river stations must be numbers in HEC-RAS. HEC-RAS will use the river stations (along with River names) for determining the order of cross sections for performing water surface profile calculations. River station numbers must increase in the upstream direction. Import options for river stations allow you to match river stations to the existing geometry, round the river station value for import, and create river stationing.

Match River Stations to Existing Geometry

The Match Import File RS to Existing Geometry RS option allows you to specify a numeric tolerance to search for duplicate cross sections in existing geometry files. This tool is useful when you are re-importing cross section data where you may have modified the stream centerline or cross section layout. The newly computed river stations may differ from the original stationing due to small spatial changes made in the


5-6

GIS. This tool is also convenient if you are updating cross sections that have river stations that were rounded during the initial importthe data.

Round River Stations

GeoRAS may export the river stationing to more decimal places than are necessary. You can round the river stations to the precision appropriate for your study.

Create River Stations

By default, GeoRAS will compute river stations in the unit system of the digital terrain model and will use a zero station at the most downstream end of each river reach. If you wish to change the ristationing you can do so in the GIS, or you can do so during the import process. It is recommended that you document the methodused if you change the river stations. Documenting the method used to compute new river stations will be important if you need to re-import cross-sectional data – the river station identifier is the link between the GeoRAS generated data and the HEC-RAS data.

Storage Areas and Connections

The Storage Areas and Connections tab, shown in Figure 5-5, allowyou to specify storage areas and storage area connections to import and what name to import them with. You can choose to import thestorage area outline and/or the elevation-volume relationship.

of

ver

s


5-7

ys verify that nded to import.

ta does not have any significant e corrected to properly

present the physical system.

The cross section plots, tables, and tools in HEC-RAS will assist you in ection Plot and ualize the

imported cross section data.

phical Cross Sectional Editor is advantageous because not only can you visualize the cross section, you can add, delete, and modify cross section properties. The editoris accessed from the HEC-RAS

ata editor by selecting the Tools | Graphical Cross dit menu, as shown in Figure 5-6.

Figure 5-5. Storage Areas and Connections import options.

Completing the Geometric Data

After importing any data into HEC-RAS, you must alwathe data imported is representative of the data you inteNext, you must verify that that the daerrors or gaps. Data that is incomplete must bre

scrutinizing, entering, and modifying data. The Cross SGraphical Cross Section Editor are two good ways to vis

Graphical Cross Section Editor

The Gra

Geometric DSectional E


5-8

shown in Figure 5-7, allows you to

Figure 5-6. Accessing the Graphical Cross Section Editor.

The Graphical Cross Section Editor,

visualize the shape of the cross section and all of the properties on the cross section. You can also move, add, or delete objects in the cross section from the editor. To change modes, right click in the

lect from the cmenu the mode you wish toThe Move Object mode is the default when entering the editor.

There are also tools for stations and Manning n valueditor.

editor and se ontext work in.

moving bank es in the

Figure 5-7. HEC-RAS Graphical Cross Section Editor.


5-9

Manning’s n Values

Several tables are also convenient for verifying and enManning’s n value data may be entered using the Tabln or k values menu item.

tering data. es | Manning

Hydraulic structure data may be imported from the GIS. Bridge data

o be

d must

Figure 5-8. Entry of Manning's n values through tables in HEC-RAS.

Bridges and Hydraulic Structures

will be the most incomplete. Likely the bridge deck top-of-road information will have been imported, but the bridge opening information, piers, and modeling approach information will need tcompleted. As illustrated in Figure 5-9, often, only the bridge abutment information is included in the digital terrain model anbe completed. Bridge data is completed in the Bridge and Culvert Data editor accessed from the Geometric Schematic.


5-10

Figure 5-9. Completion of bridge data imported from GeoRAS.

Lateral structures should be examined to verify that the structure begins and ends in the correct location in the HEC-RAS model. If the river station for the lateral structure was not verified prior to GeoRAS export, it must be verified in HEC-RAS. Inline structure and lateral structure data will need to be completed, much like the bridge data. Top–of-weir profile data, gate geometry and settings, and computation methods will need to be modified and entered.

Cross Section Points Filter

Cross sections in HEC-RAS can only have 500 station-elevation points. If you try to run the simulation with more than 500 points the HEC-RAS interface will stop and inform you of the cross sections that have too many points.


5-11

To filter cross section points, select the Tools | Cross Section Points Filter from the Geometric Data Editor. You can filter cross sections at gle cross section or at multiple locations. You also have the choice of filtering based on the slope between each point or based on minimizing the change in area in the cross section.

menu itema sin

alog.

Completing the Flow Data and Boundary Conditions

rom the RAS GIS Import File. You will nsteady Flow file and enter flow

in

name.

Examining

After performing a steady or unsteady flow simulation, you must verify the hydraulic results using the standard plots and tables available in

Figure 5-10. Cross section points filter di

Flow data will not be imported fhave to create a Steady Flow or Uchange locations and boundary condition data. It is also importantsteady-flow simulations to label the flow profiles with a meaningful

Results


5-12

HEC-RAS. You must also verify that the computed water surface profile(s) will result in an appropriate floodplain. For instance, cross sections should be closely spaced together around bends in the river and extend across the entire floodplain. Cross sections should also be wide enough to allow for nonlinear floodplain delineation between cross section.

Prior to exporting the water surface profile results, you should also verify the bounding polygon. The bounding polygon (discussed in detail in Chapter 6) limits the area that will be used for floodplain delineation. This is especially important when the river system has levees that may be overtopped by one of the water surface profiles. If

m is overtopped, you will need to verify that the levees downstream are turned off, as well.

e

s menu item. You must then select the Profile and River Reach for which to plot data.

a levee upstrea

Bounding polygon information for each profile can be verified in thGeometric Data editor. Select the GIS Tools | Plot GIS Reach Profile Bound

Figure 5-11. GIS bounding polygon information (thick line) for a leveed system (a) contains flow and (b) is overtopped.

Exporting the HEC-RAS Results

After steady or unsteady flow simulation, HEC-RAS results can be exported for processing in the GIS by GeoRAS. Select the File | Export GIS Data menu option from the main HEC-RAS interface as shown in Figure 5-12.

a.) Levee contains flow b.) Levee is overtopped


5-13

Figure 5-12. Access the GIS export options from the main HEC-RAS interface.

T wn i w you to choose the file location to write the GIS information to and select the output options. B h ta will be written to the RAS GIS Export file (.RASExport.sdf).

he dialog sho n Figure 5-13 will allo

e sure to select t e water surface profiles of interest. The GIS da

Figure 5-13. GIS export options in HEC-RAS.


5-14

There are many GIS Export options available from HEC-RAS. WithHEC-RAS 4.0 or later, the option to select the River Reach of interest and/or Storage Areas is provided. The user may also choose to expthe velocity, shear stress, stream power, or ice data for interpolatioand mapping using HEC-GeoRAS.

ort n

If you choose to export velocity, shear stress, or stream power data, ill also be export along with the Active Water

Surface Extents. This is necessary for improved interpolation.

Geometric data options are also available for export. The user may oss Section Surface Line” for the entire cross only. Upon import into GeoRAS, a 3D feature

g

the Bank Stations w

You should take care to only export the water surface profiles and parameters of interest. The export file can grow very rapidly and importing to the GIS can become burdened with excessive data.

select to export the “Crsection or the channel class of the cross sections will be created. This is helpful for doinsurface analysis. Additional properties may be export for visualization in a GIS; however, HEC-GeoRAS will import only the bank stations property.

Chapter 6 RAS Mapping

6-1

C H A P T E R 6

RAS Ma

eration of floodplain maps from exported HEC-RAS simulation results. Floodplain boundary and

created from exported cross-sectional water surface elevations. Mapping of the water surface

C-

• Data Storage

Importing t

HEC-GeoRAS does not read the .RASExport.sdf file directly. It must ML format. After converting the data from the

e data is read into the GIS and HEC-RAS results

ad directly into HEC-GeoRAS. To convert an SDF file to the XML format,

pping

HEC-GeoRAS facilitates the gen

inundation depth data sets may be

extents as point locations, velocities, and ice information are also available.

Chapter 6 discusses processing exported HEC-RAS results using HEGeoRAS.

Contents • Importing the RAS GIS Export File

• Inundation Mapping

• Velocity Mapping

• Ice Mapping

he RAS GIS Export File

first be converted to XSDF to XML format thare processed.

SDF Conversion to XML

The spatial data format (SDF) file written by HEC-RAS is not re

select the (Convert Rinterface. This will invok

AS SDF to XML File) button on the GeoRAS e the dialog, shown in Figure 6-1, allowing

you to choose the RAS Output File and will automatically create a default XML File name in the same directory (.xml file extension). The file will be created when you press OK.


6-2

or converting RAS SDF file to XML file format.

In order to process HEC-RAS results, you must first identify the g to perform – a new analysis or continuing ing analysis. This is performed through the Layer

parameters. A summary of data inputs is provided in Table 6-1.

Figure 6-1. Dialog f

Layer Setup

analysis you are goinworking with an existSetup dialog.

Select the RAS Mapping | Layer Setup menu item from the HEC-GeoRAS toolbar. The dialog shown in Figure 6-2 will allow you to specify the output data and

Figure 6-2. Floodplain mapping layer setup dialog.


6-3

Table 6-1. Floodplain mapping layer setup input options.

Description Data Input

Analysis Type Existing Analysis – changes the active Map to the

ith

analysis selected.

New Analysis – creates a new Map and directory wthe name entered.

RAS GIS Export File

Specify the XML file containing HEC-RAS results.

Terrain Single – Select the TIN or GRID for floodplain analysis.

he polygon feature class

Size s.

Multiple - Select trepresenting the terrain tiles for floodplain analysis.

Output Directory Specify the directory location. A new directory with the Analysis name will be created in the Output Directory for all results.

Output GeoDatabase

A geodatabase will be automatically created with the name of the Analysis.

Rasterization Cell Specify the grid-cell size for inundation depth grid

Analysis Type

The Analysis Type allows you to choose to work on an Existing Analyor start a New Analysis. The Analysis Type allows you flexibility in performing the floodplain analysis and modifying results. If you choose Existing, the Map (data frame) of the same name will be activated. You can then continue processing results from previous GeoRAS analysis or reporcess portions from an analysis (such as floodplain delineation). A New Analysis will be chosen each time a nset of HEC-RAS results are brought read into the GIS.

Pressing the OK button from the Layer Setup dialog will activate theexisting map or create a new map and new analysis directory based othe Analysis Type selected.

sis

ew

n

RAS GIS Export File

The RAS GIS Export File must be in the XML format. It is converted from the SDF file using the Import RAS SDF File button.


6-4

Terrain

You must specify the terrain model to be used for performing the floodplain delineation. GeoRAS allows for a DTM in the format of a TIN

rrain data may be one single data set or g multiple terrain tiles to represent very

The Rasterization Cell Size will determine the grid-cell size for the

ze

n delineation and processing time. Refine the cell size during future floodplain delineations to improve the resulting floodplain

s ad

The will be brought into the Map and data will be read from

the specified XML file. If the RAS GIS Export File is large (having numerous cross sections with velocity or other parameter data) it may

utes to read in the XML file.

The DTM will be loaded to the Map and a copy will be rasterized based

e and

or a GRID. Further, the temultiple terrain tiles. Usinlarge data sets is discussed in Chapter 9.

Output Directory

The Output Directory specifies the parent directory where you will store the post-processing results. Another directory will be created within the output directory having the name entered for the New Analysis. Water surface TINs and depths grids will be stored in the directory having the analysis name.

Output GeoDatabase

The Output GeoDatabase is created in the directory having the analysis name. All feature classes created during post-processing will be stored in the geodatabase.

Rasterization Cell Size

inundation depth grids. If the input DTM is of type GRID, the cell sizeof the GRID will be used. A smaller grid-cell size will result in longer processing time for floodplain delineation. The Rasterization Cell Sishould be based on the resolution of the DTM. As a practical consideration, start with a larger cell size and evaluate the resulting floodplai

boundary.

Read RAS GIS Export File

After establishing the post-processing data input options, RAS resultare read into the GIS for processing. Select the RAS Mapping | ReRAS GIS Export File menu option from the GeoRAS toolbar. DTM selected

take several min

on the Rasterization Cell Size and stored in the output directory for later use. The raster version of the DTM will be named “DTMGRID”. Base feature classes will be created for the cross-sectional cut lin


6-5

bounding polygons. These feature classes will be used for post-processing.

Stream Centerline

r the field name will have the profile name exported from HEC-RAS.

d

Export file, a “Storage Area” feature

Profile Definition Table

s in

A stream centerline feature class will be created in the Output GeoDatabase based on the centerline location in HEC-RAS. River and Reach attribute information will be added. This data set is not used inpost-processing by GeoRAS.


A cross-sectional cut lines feature class will be created in the Output GeoDatabase. The cut lines will represent the location of the cross sections in HEC-RAS and attribute the cross sections with water surface elevations for each profile. The feature class will have the name “XS Cut Lines” and will be added to the analysis Map.

An additional field with the name “P00n” is added to the cross-sectional cut line feature class for each water surface profile, where “00n” represents the profile number. The alias fo

Additional fields will be added to the cut line feature class such as the River, Reach, and river Station information. A field will also be addeindicating whether the cross section was interpolated.

Storage Areas

If Storage Areas are in the RAS class of polygon outlines will be created. A field for each water surface profile will be added with a corresponding water surface elevation.

Bounding Polygons

A bounding polygon feature class will be created containing a polygon feature for each water surface profile. The field ProfileID will hold a “P00n” value corresponding to the water surface profile in the cut lines feature class. A ProfileName field will also be added and will hold the profile name exported from HEC-RAS. The feature class will have the name “Bounding Polygon” and be added to the analysis Map.

A table called “ProfileDefinition” will be created and will summarize the profile names exported from HEC-RAS and the profile field namethe Cross-Sectional Cut Line feature class.


6-6

Water Surface Extents

A “Water Surface Extents” feature class will be created. These

Ice Thickness Data

e

e

features will identify the edge of the water surface as computed in HEC-RAS (not the GIS) for each water surface profile. To visualize the water surface extents for any one profile, a “Definition Query” for a specific water surface profile will be required.

Bank Stations

If bank station data are available in the RAS Export file, a feature class called “BankPoints” will be created. This data is important if you intend on performing velocity mapping.

Velocity Point Data

The “Velocities” point feature class will be created from velocity data inthe RAS Export file. The velocities are exported based on the Velocity Distribution computed in HEC-RAS, with one point at the centroid of a flow distribution location.

Ice thickness data for the Left overbank, Channel, and right overbank will be imported, if available, to the “Ice Thickness” feature class. Icthickness data is considered constant in the left overbank, channel,and right overbank.

Shear Stress Point Data

A shear stress point feature class will be created from velocity data in the RAS Export file. The shear stress data are exported based on the Velocity Distribution computed in HEC-RAS, with one point at the centroid of a flow distribution location.

Stream Power Point Data

A stream power feature class will be created from velocity data in thRAS Export file. The stream power data are exported based on the Velocity Distribution computed in HEC-RAS, with one point at the centroid of a flow distribution location.


6-7

Inundation Mapping

delineation, the “DTMGRID” data source must be present in the analysis output directory.

surface TIN from the water surface elevations attached to each cross section. Select the RAS Mapping | Inundation Mapping | Water

ion menu item to build the water surface TINs. The gure 6-3 will allow you to choose the water surface

profile(s) of interest. You can select multiple profiles using the Ctrl ave

Inundation mapping is performed using the water surface elevations on the Cross-Sectional Cut Lines feature class and is limited to Bounding Polygon features. These two feature classes must be created prior to performing the inundation mapping. Floodplain delineation also requires the digital terrain model. When using the GRID Intersection method for floodplain

Water Surface TIN Generation

The first step in the floodplain delineation process is to create a water

Surface Generatdialog shown in Fi

and Shift keys in combination with the left mouse click. You also hthe option to add (“Add Output Layers”) the TIN surface to the currentmap and to display (“Draw Output Layers”) the added layer.

ry (corresponding to the Map name) using the assigned profile name “P00n” prefixed

Figure 6-3. Select the water surface profiles to process.

A water surface TIN for each profile will be created irrespective of the terrain model. The ArcGIS triangulation method will create the surfaceusing cross sectional cut lines as hard breaklines with constant elevation.

Water surface TINs are stored in the analysis directo


6-8

with a “t”. The TIN is then added to the analysis map using the pname exported from HEC-RAS prefixed with a “t” (“t” is for TIN).

rofile

Floodplain Delineation

on is performed using the RAS Mapping | Inundation Mapping| Floodplain Delineation menu item.

el

ely

incorrectly limiting the floodplain boundary. The floodplain delineation to

The floodplain delineation method rasterizes the water surface TIN using the Rasterization Cell Size and compares it to the “DTMGRID”.

raster version of the water surface TIN is stored in the analysis tory as “wsgridP00n”.) The floodplain is calculated where the

water surface grid is higher than the terrain grid. The Bounding

in on. The depth grid is stored to the analysis directory

having the name using the water surface profile name “P00n” and ing

r

th

mooth Floodplain Delineation” option is selected, the resultant floodplain boundary will be a generalized polygon boundary of the depth grid. The floodplain boundary feature is stored in the output geodatabase in the RASResults dataset as “b” and the profile name “P00n”. The floodplain boundary is then added to the analysis map using the HEC-RAS profile name prefixed with a “b” (“b” is for boundary).

Velocity Mapping

Velocity mapping is performed by interpolating the detailed velocity data be exported from HEC-RAS at each cross section using the Flow Distribution simulation option. In order to compute the velocity distribution surface, a floodplain boundary layer must already exist for

Floodplain delineati

Floodplain delineation will use the water surface TIN and terrain modto calculate the floodplain boundary and inundation depths.

Floodplain delineation results should be carefully examined. Spuriousinundated areas may be present and should be deleted in the GIS or prevented from occurring by using levees in HEC-RAS. Inappropriatplaced cross sections may result in the bounding polygon data

process using GeoRAS is an iterative process that should be usedrefine the hydraulic model in HEC-RAS.

(Thedirec

Polygon is used to limit the floodplain only to the area modeled in HEC-RAS.

The inundation depth grid results from the water surface and terragrid comparis

prefixed with a “d”. The depth grid is added to the analysis map usthe profile name exported from HEC-RAS prefixed with a “d” (“d” is fodepth).

The floodplain boundary feature class is created based on the depgrid. The floodplain boundary is the exact outline of the depth grid. If the “S


6-9

tuhe corresponding profile. The interpolated velocity data is computed sing the RAS Mapping | Velocity Mapping menu item. The dialog

shown in Figure 6-4 will allow yprofiles that have floodplain bound

ou to choose from the water surface ary maps and velocity information.

ng velocity mapping. Figure 6-4. Selection dialog for performi

he “Velocities” point file that is loaded to the GIS, this is for visualization only. Instead, the data stored in the RASExport.xml file is used. For each profile selected,

ary to a “Floodplains.xml” file to limit the interpolation and creates a “Parameters.xml”

file to establish the input and output parameters for running the interpolation program. An example of the Parameters file is shown in

The velocity interpolator does not use t

GeoRAS exports the flwhich used

oodplain bound

Figure 6-5.

te

line is computed for each point velocity on a cross section and transitions to the next cross section using the shape

Figure 6-5. Example parameters file for running the interpolation program with HEC-GeoRAS.

Interpolation of the velocity data is done on a cross section by cross section basis. The first step in the interpolation process is to computransition lines between cross sections in the main channel and overbanks. A transition


6-10

of the stream centerline. An example of the transition lines are shown in Figure 6-6.

n

annel ly

is

Figure 6-6. Transition lines computed for velocity interpolation is done from cross sectioto cross section.

Velocity data are then interpolated along the transition lines to create known values for input into a gridded matrix solver. The main ch(as defined by the main channel bank stations) is solved separatefrom the overbanks. The floodplain boundary uses a zero-velocity boundary for the solution space. The dialog shown in Figure 6-7shown during the interpolation to provide status updates.

Figure 6-7. Interpolation status dialog keeps you updated on the progress.

Once the interpolation is complete, a velocity surface is created iESRI binary floating point format (.flt). The filename will be the profile name prefixed with the abbreviation “vel” (“velP001.flt”, for instance). A second file with the “.hdr” file extension is created which specifies the parameters for the grid. The binary raster is then converted to thESRI grid format and stored in the output directory with a “v” and the profile name “P00n”. The velocity grid is then added to the analys

n the

e

is


6-11

Map using the HEC-RAS profile name prefixed with a “v” (“v” is for velocity).

ow around objects. Care should be taken when interpreting the interpolated velocity results and

also be performed outside of HEC-floodplain

now want to ided in Appendix

d alone mode.

es are constant in Further, the

of the ice and not

After interpolation, an ESRI binary raster is created using the “ice” er is

t e

sis Map using the HEC-RAS profile name prefixed with an “i” (“i” is for ice thickness).

interpolation can be found in Appendix C, which

Shear Stress Mapping

g is performed in much the same way as the velocity mapping. After interpolation, an ESRI binary raster is created

The

S .

Note: the velocity interpolation method is an attempt to allow for visualization of the distribution of the 1-dimensionally computed velocities between cross sections. The interpolation algorithm uses limited data to determine the transition of flow from one cross section to the next and cannot predict the 2-dimensional nature of fl

formulating hydraulic conclusions.

Interpolation of velocity data may GeoRAS. This is useful if you have already performed the delineation (using a previous version of GeoRAS) andvisualize velocity data. Detailed instructions are provC on how to use the interpolation software in a stan

Ice Thickness Mapping

Ice thickness mapping is performed in much the same way as the velocity mapping; however, ice thickness data valuthe left overbank, main channel, and right overbank.floodplain boundary is used only to limit the extentsas a zero-value boundary as done for the velocity interpolation.

prefix and assigned a profile name (iceP00n.flt). The binary rastthen converted to the ESRI grid format and stored in the outpudirectory with an “i” and the assigned profile name “P00n”. The icthickness grid is then added to the analy

More details onprovides a full description of parameters and keywords for ice thickness data.

Shear stress mappin

using the “shear” prefix and assign profile name (shearP00n.flt). binary raster is then converted to the ESRI grid format and stored in the output directory with an “s” and the assigned profile name “P00n”. The velocity grid is then added to the analysis Map using the HEC-RAprofile name prefixed with an “s” (“s” is for shear)


6-12

More details on interpolation can be found in Appendix C, which provides a full description of parameters and keywords for shear stress

Stream Po

e

converted to the ESRI grid format and stored in the output directory with a “p” and the assigned profile name “P00n”.

Data Storage

g. ored

ou in

ar

ish to a mistake in

6-8.

data.

wer Mapping

Stream power mapping is performed in much the same way as thvelocity mapping. After interpolation, an ESRI binary raster is createdusing the “power” prefix and assign profile name (powerP00n.flt). The binary raster is then

The stream power grid is then added to the analysis Map using the HEC-RAS profile name prefixed with a “p” (“p” is for power).

More details on interpolation can be found in Appendix C, which provides a full description of parameters and keywords for stream power data.

HEC-GeoRAS will create numerous data sets during post-processinThe Layer Setup dialog will show you where all the data will be stduring processing. Familiarity with the data storage will assist yproperly managing data during the iterative process of floodplain delineation.

GeoRAS is set up so that all of the analysis results for a particulHEC-RAS simulation (or plan name) are stored in a single directory. This allows you to quickly manage an entire analysis. You may wdelete an entire set of post-processed data after you find the HEC-RAS model, for example, during the iterative floodplain delineation process. A sample data file structure is illustrated in Figure


Output Directory (“Floodplains”)

6-13

rocessed data.

Visualization

S to assist you your mapping effort using

e tools provided will assist you mapping and publishing your

r

Figure 6-8. HEC-GeoRAS sample data structure for post-p

Visualization tools are provided in HEC-GeoRAunderstand and interpret the results ofreadily available base mapping data. Thin creating a animation of inundationdata to a KML client (such as Google Earth, Microsoft Virtual Earth, oESRI ArcGIS Explorer).

Analysis Directory (“Steady Flows”)

“RASResults” Dataset: - - Floodplain Boundaries (“bP00n”) - XSCutlines

GeoDatabase (“Steady Flows”)

Bounding Polygons

Depth Grids (“dP00n”)

Ra

W

Ra(“w

GeoRAS project (.mxd)

ster of terrain model (“DTMGRID”)

ater surface TINs (“tP00n”)

ster of water surface TINs sgridP00n”)


6-14

2D Animation

The floodplain animation control, shown in Figure 6-9, available through the RAS Mapping | Visualization | 2D Animation menu allows you to create a movie file having the .avi file extension. The animation control provides you with a list of all layers in the Map (Map Layers), “Animation Layers”, and “Base Layers.

Figure 6-9. HEC-GeoRAS animation control allows you to create a movie file (.avi).

Base Layers are static layers that will be visible for the entire animation and must be displayed prior to accessing the animation control. After adding the layers to be animated to the “Animation Layers” list they can be ordered and removed using available tools. Buttons are also provided to add the floodplain boundaries and depth grids. The Add Floodplains button will add all layers preceded by a “b”, while the Add Depth Grid button adds all layers preceded by a “d”. The animation list also allows you to set the relative “Wait Time” (in seconds) for each layer.

The animation file will be created based on the “Movie Options” specified. This is accomplished by creating bitmaps of the display with the layers displayed in the order of the “Animation Layers” list. The bitmaps are then combined to create an animation file (.avi). If you wish to keep the bitmaps on disk, select the “Keep Images at Movie Location” option. You should enter a movie file name and output location for the output files.


6-15

Publish Layers to KML Client

Layers created in GeoRAS can be published to the KML format using the RAS Mapping | Visualization | Publish Layers to KML Client

ng control, shown in Figure 6-10, lists ent map. To create a KML file, select t, specify the output directory location,

and press the Create KML Files button. The KMZ file that is created is a compressed KML file.

menu item. The KML publishithe layers available in the curr(highlight) the layer of interes

AS can be exported to the KML format for

[It is a known issue that Google Earth has a limitation as to the size/number of points that can be displayed using a KML file.

ended that floodplain boundary layers are orting to KML.]

at has been adopted by the Open GIS Consortium (OGC). Data are stored in latitude and longitude as in the

Post-Processing Utilities

e

Figure 6-10. Layers created in HEC-GeoRdisplay in KML viewers.

Therefore, it is recommgeneralized prior to exp

About KML

KML is the Keyhole Markup Language made popular by its use in Google Earth. It is a standard th

World Geodetic System of 1984 (WGS84) coordinate system.

Post-processing utilities are available to assist you in performing mapping and visualization results. The options available from the RAS Mapping | Postprocessing Utilities are: Copy Analysis, DeletAnalysis, Clip GRID, and Symbolize Rasters.


6-16

Copy Analysis

ase from an nto the

nu item u may

performed , you can

e cell size model will

Copy Analysis allows you to copy the underlying geodatabexisting analysis so that you don’t have to re-read the data iGIS from the RAS GIS Export file. The Copy Analysis meinvokes the Layer Setup dialog, as shown in Figure 6-11. Yoselect from any of the “Existing Analysis” that have been and must enter the name for the “New Analysis”. Optionallyspecify a new “Rasterization Cell Size” to identify the impacts ofrefining the grid-cell size for delineation. If you change ththe terrain model will be re-sampled otherwise the terrainbe copied, as well.

manually, if desired.

Clip GRID

The Clip GRID option is provided to assist you in synchronizing the inundation boundary polygon with the depth grid. This tool, shown in Figure 6-12, is useful for clipping the depth grid to match the

Figure 6-11. The Copy Analysis option will create a copy of an existing analysis but allowthe user to modify the analysis parameters.

Delete Analysis

The Delete Analysis menu item allows you to delete an existing analysis from the HEC-GeoRAS configuration file and removes the corresponding Map. The data, however, must be deleted from disk


6-17

boundary of a floodplain that has been manually editfloodplain extents.

ed to reduce the

Figure 6-12. Depth grids can be clipped to extents of a floodplain boun

Symbolize Rasters

The Symbolize Rasters option is used to assign an identical symbology to each depth grid created by GeoRAS. This is useful if yflood depth grids representing the rise and fall of a flood hand you want to use a consistent symbology to visualizrange for each depth grid.

In order to use the Symbolize Rasters tool, shown in must set up the symbology for one raster that will act as tTypically, this will be set to display a color for the minimudepth and maximum flood depth for all grids. The rast

dary polygon.

ou have many ydrograph

e the depth

Figure 6-13, you he template. m flood

er template is o he list of selected as the “Source Raster” which is then applied t

selected rasters. t

you to assign the same symbology to Figure 6-13. The Symbolize Rasters tool allows

ultiple raster datasets. m

Chapter 7 Example – Data Import

7-1

C H A P T E

Exam

This chapte nerated outside of HEC

usin incompat nt to modify a

The data ta set that is referenced i

•

•

•

•

• Attribute Feature Classes

Start a New ArcMap project

The fi mport ex p and load

project (“Import.mxd”)

Maps are is important

to ws” which maps hol “Geometry Import”.

hrough the proper

et ArcMap do the rect by

selecting the tab as shown

in

R 7

ple – Data Import

r provides an example for importing data ge-GeoRAS for ArcGIS and importing it into a GeoRAS

geodatabase. This is important for users that have created data sets g other tools, specifically HEC-GeoRAS for ArcView 3.2 or in

ible versions of the geodatabase (like ArcGIS 8.x), and wand re-extract data using GeoRAS in ArcGIS.

set used for this example is the Wailupe River dan previous HEC-GeoRAS user’s documentation.

Main Tasks Start a New ArcMap project

Generate the GeoRAS Feature Classes

Import Data to Feature Classes

Assign HydrolDs to Features

rst step is to use GeoRAS to generate a geodatabase to iisting data into. This is done in ArcMap. Start ArcMa

the HEC-GeoRAS extension. Save the ArcMap in a directory of your choosing.

Next, create a Map (data frame) for the geometric data. added through the ApUtilities | Add Map menu item. It

add maps using the ApUtilities so that GeoRAS “knod data. For this example, the map’s name is

Assign a coordinate system to the map. You can do this tmap properties or you can load a data set that has the coordinate system. Add the terrain TIN (“wai_tin”) and l

work for you! Verify that the coordinate system is corright-clicking on the Geometry Import map and Properties menu option. Select the Coordinate System

Figure 7-1, and verify the coordinate system is correct.


7-2

7-1. Map Properties dialog with the Coordinate System tab shown.

t, you are AS could do gure 7-2 will

be i e class. and location

mport.mxd”.

Figure

Generate the GeoRAS Feature Classes

Once the project is saved and the coordinate system is seready to create the GeoRAS feature classes. Select the RGeometry | Create RAS Layers | All menu item. (Youeach feature class one at a time.) The dialog shown in Fi

nvoked to allow you to enter the names for each featurPressing OK will build a geodatabase based on the name of the ArcMap project. In this case, a geodatabase called “Import” was created and is stored in the same directory as the “I


7-3

gure 7-2. Dialog allowing user specified feature class names.

Once the feature classes have been erated, they will be added to the

ArcMap table of contents. You may remove any data sets you don’t plan on using from the Table of

nts. A blank feature class for e data set will remain in the

geodatabase. For this example, you l next import existing data into

the blank feature classes. First, however, save your project and

close ArcMap.

Fi

gen

Conteth

wil

then


7-4

Import Data to Feature Classes

Start ArcCatalog and navigate to the geodatabase (“Import”), as t

the same directory.

Data is imported into existing feature classes using ArcCatalog. Because ArcCatalog will be accessing data, you must make sure it is not being used in another ArcGIS session (such as ArcMap).

shown in Figure 7-3. Note that the geodatabase and map documenare stored in

Figure 7-3. Browsing in ArcCatalog.

Double-click on the GeoDatabase and classes. Right-click on a feature class) and select the Load Data me

DataSet to access the feature class (choose the River feature

nu item (see Figure 7-4).

o import data. Figure 7-4. Right-click on a feature class t


7-5

Load Data Process

The load data process is used to import features and assign attributesto fields. The process is enu

merated in the following steps.

y navigating to the the “River” shapefile).

1. Select the data source to import bassociated shapefile (stream.shp is

8. Click the Add button to choose the data set. Click the Next button to proceed.


7-6

9. Click Next in the next dialog.

10. The dialog will allow you to match the source fields to the fields in the geodatabase. Field names will be similar, if not identical, in the geodatabase and shapefiles. Match the fields for the data you wish to import. Any attribute infomation not imported can be completed in ArcMap using GeoRAS. Click Next when the fields have been matched.


7-7

11. You can choose to import all features or load those that satisfy an attri ry. Select an option and Click Next.

bute que

12. The data is imported and a summary dialog provides results.

Repeat the data import process for each feature class.


7-8

Assign Hy

o assign a Start ArcMap work, each

droIDs to Features

After importing data for each feature class, you will need tHydroID to each feature. This is performed in ArcMap. and open the “Import” project. For GeoRAS functions tofeature must have a unique HydroID.

Select the ApUtilites | Assign UniqueID menu item as shown in Figure 7-5.

Figure 7-5. Assigning HydroIDs is performed through the ApUtilities men

The dialog shown in Figure 7-6 will be invoked allowing yothe feature classes (Layers) to which to assign HydroIDs. Press Select All button.

u.

u to choose the

Figure 7-6. HydroID assignment options.


7-9

Also choose YES to overwrite existing IDs and choose All Features. Press OK and the HydroID field will be populated for each layer that has features. A status dialog (see Figure 7-7) will inform you of how many IDs were populated.

Figure 7-7. Successfull assignment of HydroIDs dialog.

Attribute F

ID

yer,

classes. e feature

eature Classes

You must now verify that each feature was assigned a unique Hydroand that each feature has the appropriate attributes. Assuming that you imported all of the field data and the HydroID process was successful, you are done.

A good way to populate the attributes of the XS Cut Lines lahowever, is to run through the RAS Geometry | XS Cut Line Attributes menu items. In doing so, you can be sure that the features have been attributed based on the other feature After populating attributes, open the attribute table for thclass and verify that the data was appropriately populated.


7-10

Chapter 8 Example Application

8-1

C H A P

use the HEC-lic model ides a step-by-step

HEC-RAS and HEC-RAS.

our example with a TIN

model will

The figures in this example are intended to demonstrate the GeoRAS lically

Load HEC-GeoRAS

Start the ArcMap program. Verify that the 3D Analyst and Spatial Analyst extensions are installed and loaded by selecting the Tools | Extensions menu item. Select the extensions as shown in Figure 8-1 – if they are not available, you will need to install them.

T E R 8

Example Application

This chapter provides a detailed discussion of how to GeoRAS extension in ArcGIS for supporting hydraudevelopment and analysis with HEC-RAS. This provprocedure for developing geometric data for import into how to develop GIS data sets from results exported from

This example is for the fictional Baxter River that majestically meanders through Tule Town, USA. We begin of the river system that incorporates detailed terrain data for both the main channel and adjacent floodplain. The detailed terrainbe the basis for this example.

process and underlying principles and may not be hydrauaccurate. For more discussion on the steps addressed in this examplerefer to Chapters 3-6.

Main Tasks • Load HEC-GeoRAS

• Start a New Project

• Create Contours from a DTM

• Create RAS Layers

• Generate the RAS GIS Import File

• HEC-RAS Hydraulic Analysis

• Import the RAS GIS Export File

• Generate GIS Data from RAS Results


8-2

ap. To load the n ArcMap

be added to u may dock

Figure 8-1. Load the ESRI extensions for use with GeoRAS.

The HEC-GeoRAS tools are loaded as a toolbar in ArcMGeoRAS toolbar, select Tools | Customize from the maiinterface (see Figure 8-2). Place a check in the checkbox corresponding to HEC-GeoRAS. The GeoRAS toolbar will the interface. Press the Close button when finished. Yothe toolbar where desired.

Figure 8-2. Add the HEC-GeoRAS toolbar to the map.

Start a New Project

a. If opy

o an appropriate directory. For this example, the project directory has been named “Baxter Example”.

Select the File | Save menu item to save the ArcMap document. Navigate to the project directory and enter the project name for the ArcMap document (“Baxter92” is used for this example).

Stop! You should save your project and save it often. Have you determined the directory structure for where you want to store the GeoRAS data layers? Decide on the location to store your GIS datthe directory does not exist, create it using a file manager. Move/cthe terrain layer t


8-3

Add a Map

Add a map to the ArcMap document by selecting the ApUtilities | Add New Map menu item. Enter the name “RAS Geometry” for the name and press OK.

Coordinate System

Set the coordinate system for analysis for the RAS Geometry map. The coordinate system must match that of the terrain model! The simple way to do this is by adding the DTM to the map. The projection information for the map will be set based on the first data set loaded.

Add the “Baxter_tin” TIN to the map by pressing the Add Data button and navigating to the location of the DTM. The TIN is added to the map. Uncheck the box next to the DTM layers name to stop the terrain from rendering.

Right-click on the map, select the Properties menu item. In the Data Frame Properties dialog click on the Coordinate System tab anverify the coordinate system as shown in Figure 8-3.

d

Figure 8-3. The coordinate system for the map must be set prior to using GeoRAS.


8-4

Create Contours from a DTM

ing in the map. Contour lines are a good source of data for visualizing the

Select the 3D Analyst | Surface Analysis | Contour menu item. eet and an output location. Press d added to the RAS Geometry

dequate information. But if you zoom in, you will likely want to see the channel defined by

s

You most likely have noticed that even small terrain models take quite some time to render. This delay during a screen refresh can be quite time consuming, while you are digitizing features or panning/zoom

terrain and will redraw more quickly.

Enter a contour interval of 5 or 10 fOK. The data set will be created anmap.

While you are zoomed out, the contours provide a

the DTM. To use the contours in harmony with the terrain model, set the Scale Range property of the “Baxter_tin” to only display features when zoomed in (not displayed when zoomed out beyond 1:8,000) ashown in Figure 8-4.

Figure 8-4. Use the Scale Range property of layers to display only when needed.

Next, decide how you want the contours to display. You can set the contours to be displayed until you zoom in and have them turn off when the TIN is rendered by setting the Scale Range property of the contours layer. The use of scale to render layers is demonstrated in Figure 8-5 through Figure 8-7.


8-5

Figure 8-5. Contour lines near a junction, scale ~ 1:10,000.

Figure 8-6. DTM rendered with contour lines at junction, scale just smaller than 1:6,000.


8-6

Figure 8-7. DTM rendered without contour lines, scale just greater than 1:6,000.

yers

In this section, you will create and edit a series of layers collectively referred to as the RAS Layers that are stored in a geodatabase. The RAS Layers are the basis for the geometric data extracted in the GIS for hydraulic analysis in HEC-RAS. The RAS Themes you will create include: Stream Centerline, Cross-Sectional Cut Lines, Bank Lines, Flow Path Lines, Bridges/Culverts, Ineffective Flow Areas, Blocked Obstructions, Land Use, Levee Alignments, Lateral Structures, and Storage Areas.

GeoDatabase

Create RAS La

To create a new geodatabase with empty feature classes, select the RAS Geometry |

. This will create a geodatabase with the he same location as the ArcMap document

The RAS Layers are stored in a geodatabase.

Create RAS Layers | Allname “Baxter92.mdb” in t(“Baxter92.mxd”). Each feature class is added to the map with a unique line symbol style. You will now need to create features for each RAS Layer.


8-7

Stream Centerline

The Stream Centerline is used to establish the river reach network. The river network must be digitized in the direction of flow with reach end points coincident at junctions.

Figure 8-8. River network for the Baxter River.

Based on Figure 8-8 you have a general idea of what the river system looks like: the Baxter River flows East to West, from the Upper Reach to the Lower Reach, with the Tule Creek Tributary dividing the Baxter River into the two reaches. You will need to digitize the stream centerlines for the three river reaches shown.

Start editing the geodatabase by selecting the Editor | Start Editing menu item. Verify that you are selecting the “Baxter.gdb”. The stream centerline must be created in the direction of flow, so start at the top end of the river and zoom in so that the channel is easily identified.

Select “Create New Feature” for the Task and “River” for the Target feature class. Select the Sketch tool and begin digitizing the line in the downstream direction. (Left-click drops a vertex.) Continue digitizing the line until you reach the junction. If you need to pan,

ol (or hold down the “C” key to interrupt the he map, and re-select the Sketch tool (or

release the “C” key) to continue di ng. To finish the reach line at

the junction after creating all the reaches.

simply select the Pan toedit mode), pan through t

gitizithe junction, double-click to drop the endpoint.

Digitize each river reach. There are three river reaches in total, with one junction at the confluence of Tule Creek. You will create


8-8

Creating a Junction

To create a junction, the endpoints ofWhile in Edit mode, select “Modify Featursnapping tolerance, by selecting the the General tab, set the Snapping Tolerance

Next select the Editor | Snapping men

each reach must be coincident. es” for the Task. Next set the

Editor | Options menu item. On to “10” map units.

item. Click on snapping to uthe End points for the River layer, as shown in Figure 8-9.

Figure 8-9. Turn on snapping properties for individual layers.

rab the endpoint of a river reach line by pressing and holding the left mouse button. Move it towards another

Next, select the Edit tool and g

reach endpoint. When the point is within the snapping tolerance, asketch of the endpoint will appear and snap to the endpoint. Release the mouse button and the endpoint will snap. The progression of steps to snap endpoints in illustrated in Figure 8-10.

Figure 8-10. Progression for creating a junction using snapping.

Repeat the snapping process for the other reach. Verify that the reach network has been created in the downstream direction by changing the line symbol to include an arrow at the end of the line. In a later step, you will use the GeoRAS tools to double-check the connectivity.

River and Reach Names

Each river must have a unique river name, and each reach within a

river must have a unique reach name. Use the (River Reach ID) tool to give each river reach a name.

Click on the River Reach ID tool to make it active. Use the cursor to me dialog (shown in select each river reach. The River and Reach Na

Figure 8-11) will appear allowing you to enter the river and reach name. For this example, the Baxter River has an Upper Reach and a Lower Reach and Tule Creek is a Tributary.


8-9

Figure 8-11. River Reach name assignment dialog.

After labeling each River reach, look at the attributes for the River layer. To open the attribure table, right-click on the River layer and

u item. Note the fields that are Reach. The HydroID field

for the River pe), OID (unique

select the Open Attribute Table menin the attribute table: HydroID, River, and data were automatically populated - you entered the data and Reach fields. The Shape (link to the feature’s shaobject identifier for the feature), and Shape_Length (length of the line) fields will also be automatically populated as the data are created.

Figure 8-12. Stream Centerline attribute table.

Network Connectivity

To verify the river reach connectivity, select the RAS Geometry | Stream Centerline Attributes | Topology menu item. The fields FromNode and ToNode will be populated with integer data. Verify that the endpoints at the junction all share a common node number. The complete attribute table for the River layer is shown in Figure 8-13.

enterline Attributes |

downstream endpoint of the reach. The FromSta and ToSta data are “backwards” from the FromNode and ToNode because the actual river stationing is calculated from downstream to upstream!

Figure 8-13. Completed Stream Centerline attribute table.

Lastly, run the RAS Geometry | Stream CLengths/Stations menu item. This computes the length of each reach for determining the cross-section river stationing. The FromSta and ToSta fields will be populated with the FromSta being the


8-10

Bank Lines

stations; however, the bank lines data may be required for post-

d k lines

river.

An example of the bank lines near the confluence is shown in Figure

The Bank Lines layer is used to identify the main channel conveyancearea from that of the overbank floodplain areas. This layer is not required and there are good tools in HEC-RAS for assigning bank

processing of RAS results for velocity analysis and ice analysis. Identification of the main channel will also provide greater insight intothe terrain, movement of water in the floodplain, and in identifying non-conveyance areas.

While in Edit mode, make sure the Task is “Create New Feature” anthe Target is “Banks”. Select the Sketch tool and digitize banat the edge of the main channel. Accurate digitizing may require that the terrain model is displayed. Digitize a bank line for each bank ofeach river reach – bank lines may be continuous or broken for a

8-14.

d by the Bank Lines layer.

ines

urface

Figure 8-14. DTM overlai

Flow Path Centerl

The Flow Path Lines layer is used to determine the downstream reach lengths between cross section in the channel and overbank areas. A flow path line should be created in the center-of-mass of flow in the main channel, left overbank, and right overbank for the water sprofile of interest.

Select the RAS Geometry | Create RAS Layers | Flow Path Centerlines menu item. True, you already have generated this feature class, but GeoRAS will handle the data management. Allow


8-11

the default name of “Flowpaths” and press OK. A dialog will be invoked (see Figure 8-15) asking if you want to copy the stream centerline features to the flow path lines layer. By choosing “Yes”, you

oose Yes. won’t have to re-digitize the main channel flow path. Ch

Figure 8-15. Stream centerline features will be copied to the flow path lines

Make sure you are in Edit mode. Select “Create New Featurthe Task and “Flowpaths” as the Target. Digitize the ovpath lines in the downstream direction, following the movemenwater. An example of flow path lines on the Upper Reach ofRiver is shown in Figure 8-16.

layer.

e” for erbank flow

t of Baxter

Label the flow path lines using the

Figure 8-16. DTM overlaid by the Flow Path Lines layer.

Label Flow Path Lines

(Flowpath) tool. Use the cursor to select a flowpath. Upon selection, the dialog shown in Figure

lect the corresponding label from the dropdown list for the Left overbank, main Channel, or Right overbank. 8-17 will appear. Se


8-12

Figure 8-17. Each flow path must have an identifier of "Left", "Channel", or "Right".

Verify that the flow path type has been identified for each flow path by

from the DTM. The intersection of

e

opening the flow path attribute table and verify that the LineType field has data for each feature.


Cross-sectional Cut Lines are used to identify the locations where cross-sectional data are extracted the cut lines with the other RAS Layers will determine bank station locations, downstream reach lengths, Manning’s n values, ineffectivareas, blocked obstructions, and levee positions. An example cross section layout is shown in Figure 8-18.

Figure 8-18. XS Cut Lines should span the entire floodplain.

of er the Path

ing

Cut lines should always be located perpendicular to the directionflow and oriented from the left to right bank. Cut lines must coventire extent of the floodplain to be modeled. Creating the FlowCenterlines layer prior to creating the cut lines will assist you in layout the cut line perpendicular to flow.


8-13

Make sure you are in Editing mode. Select “Create New Feature” fothe Task and “XSCutLines” as the Target. Digitize the cut lines from the left to right overbank as necessary to capture the floodplain

r

geometry. Dog-leg the cut lines perpendicular to flow.

Previewing Cross Sections

The station-elevation data that will be extracted from the terrain model can be previewed using the XS Plot tool. This is useful to check that the cross section will span the entire floodplain to high ground and to identify the possible flow distribution in a cross section. To preview a cross section, follow the steps listed below.

1. Select the (XS Plot) tool.

2. Select the cross-sectional cut line of interest.

3. The cross section win Figure 8-19.

ill be plotted in a new window, as illustrated

Figure 8-19. Example cross section plot.

The cross section plot title will contain the River, Reach, and Station information if the attributes have been computed for the cross section.


8-14

Attributes

Attributes are added to the Cross-Sectional Cut Lines layer from tRAS Geometry | XS Cut Line Attributes menu. Each attribcomputed based on the intersection of the cut lines with another l

Select the River/Reach Names menu item. This item will add rivand reach names to each cut line based on the intersection with tstream centerline. If the process fails to run to completion, stopfix your data prior to continuing.

Next, run the Stationing menu item. This will add a river stateach cross section based on the intersection with the stream centerline. Again, if the process fails to run to completion, stop ayour data prior to continuing. However, this menu item will mostlikely work if the river reach names were successfully assigned.

Select the Banks Stations menu item to add the bank station locations to each cross section. Lastly, use the Downstream RLengths menu item to assign reach lengths based on the flow patlines. You should verify that each cut line has been assigned a reach length.

he ute is

ayer.

er he

and

ion to

nd fix

each h

table and looking at the associated field for the

ght the

Bridges and culverts are treated much like cross sections. Make sure dit mode. Select “Create New Feature” for the Task and s the Target. Digitize the cut lines from the left to right

If any operation fails to attribute you can find the problem cut line by opening the attribute “first” record that has a zero value. This indicates the computation was not successful and no value could be assigned. Highliproblem cut line and zoom to the selected feature in the map to identify (and fix) the origin of the issue.

Extract Elevations

Select the RAS Geometry | XS Cut Line Attributes | Elevations menu item to extract elevations from the terrain model. The elevation extraction process will convert the 2D features to 3D features. This will result in the generation of a new feature class. Elevations will be extracted at the edge of each triangle in a TIN or from the center of each GRID cell.

Bridges/Culverts

you are in E“Bridges” aoverbank down the centerline of each bridge/culvert crossing.

Use background data, such as an aerial photo to locate bridge crossings. Final placement should be determined based on the terrainmodel so that the road centerline falls on the high ground of the approach. An example bridge location is shown in Figure 8-20. Note


8-15

how the high ground ends near the channel at the bridge opening. Bridge deck information will need to be completed in HEC-RAS.

Figure 8-20. Locate bridge cut lines at the road centerline to capture high ground.

Attributes

After digitizing each bridge location you will need to assign River/Reach Names and river Stations as done for the cross sections. These options are under the Bridge/Culverts menu item. Next, you will supply some bridge information in the attribute table. (You will need to be in Edit mode.) Enter the distance to the next cross section upstream in the USDistance field and the width of the bridge deck (in the direction of flow) in the also a NodeName field provided for you to e

TopWidth field. There is nter a short description of

the bridge. Example attribute data for bridges is shown in Figure 8-21.

Figure 8-21. Example attribute data for bridges.

Extract Elevations

Select the RAS Geometry | Bridges/Culverts | Elevations menu item to extract elevations from the terrain model. The elevation


8-16

extraction process will convert the 2D fewill result in the generation of a new feat

Ineffective Flow Areas

Ineffective flow areas are used to identify the floodplain. They are typically used aroundineffective areas behind the bridge abutmentand expansion zones.

atures to 3D features. This ure class.

non-conveyance portions of bridges to identify

s through the contraction

h

e flow area data will only be extracted at the

Make sure you are in Edit mode. Select “Create New Feature” for the Task and “IneffectiveAreas” as the Target. Digitize the polygons using the Sketch tool to represent the ineffective flow areas around the bridges you created earlier. One polygon should be used for eacineffective area. An example set of ineffective flow areas is shown inFigure 8-22. Note that although the contraction/expansion zones arnon-linear the ineffective intersection with the cut lines.

Figure 8-22. Example ineffective flow areas at a bridge.

After digitizing the ineffective areas, the positions and elevations at the cross sections are extracted. Select the RAS Geometry | Ineffective Flow Areas | Positions menu item. Data will be extracted for each ineffective area and saved to a table named “IneffectivePositions” (by default), as shown in Figure 8-23, which defines the beginning and end location of the ineffective area and the trigger elevation. You can override the default trigger elevation by


8-17

entering an elevation (like the top-of-road elevation) in the field. A dialog will also allow you to “keep currenyou had previously entered an elevation for a

UserElev t user elevations” if

particular cross section.

e impact of large buildings built in the floodplain – areas that are not represented in the DTM.

” for gons

ow in the

Figure 8-23. Ineffective flow area data extracted at cross sections.

Blocked Obstructions

Blocked obstructions are used to remove flow area from cross sections and may be used to represent th

Make sure you are in Edit mode. Select “Create New Featurethe Task and “BlockedObs” as the Target. Digitize the polyusing the Sketch tool to represent the area blocking out flcross sections.


8-18

Figure 8-24. An obstruction (building) to flow in the floodplain is represented here using a blocked obstruction.

After digitizing the blocked obstructions, extract the positions at each cross section by selecting the RAS Geometry | Blocked Obstructions | Positions menu item. Data will be extracted for each obstruction and saved to a table named “BlockedPositions” (by default) as shown in Figure 8-25. You may enter an elevation for the top of each building in the UserElev field for each cross section.

gure 8-25. Blocked obstruction positions table.

Land Use

The Land Use layer is a polygon data set used to establish roughness oefficients for each cut line. The Land Use layer must not be a

“multi-part” data set for the GeoRAS methods to function (and there may be no gaps along a cross section). At a minimum, the land use data set must have a field that holds descriptive information about

Fi

c


each polygon. In this example, the field LUCode holds a description such as “Park”.

You may digitize your own polygon data set or load the example data provided. Building a land use data set with numerous polygons is quite tedious. We will skip this and use the data set provided.

Remove the Land Use feature class built previously. Load the Land Use feature provided in the “Baxter.mdb” database. The land use data provided has numerous land use categories and even more polygons (as shown in Figure 8-26), so the first thing you need to do is assign an n value to each polygon.

Figure 8-26. Land use data for the Baxter River area.

Use the RAS Geometry | Manning’s n Value | Create LU-Manning Table menu item to create a summary table of land use data. In the dialog provided (see Figure 8-27), select the LUCode field for the Landuse field and press OK.

8-19


8-20

Figure 8-27. Create a summary table of land use types in which to enter n value data

A table name “LUManning” will be created summarizing all of the lause typ

.

nd es and allowing you to enter just one n value per land use.

Make sure you are in Edit mode and open the “LUManning” table. values is Enter an n value for each land use type. An example of n

provided in Figure 8-28.

ill

Figure 8-28. Summary of land use type and associated n values.

Once the summary table is complete, you need to extract the n values along each cut line. Select the RAS Geometry | Manning’s n Value | Extract N Values menu item. The dialog shown in Figure 8-29 wbe invoked. You will need to select LUManning as the Summary Manning Table. Press OK to extract the data.


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Figure 8-29. Extracting n values can be done from the Land Use layer or a summary n

the

value table.

Manning’s n value data are extracted for each cross section and reported to the “Manning” table. The position of the start of the n value as a fraction along the cut line and the value are reported to table, as shown in Figure 8-30.

t impede or

Figure 8-30. Example Manning's n value data extracted along cut lines.

Levee Alignments

The Levee Alignments layer is used to identify features thadirect the flow of water from moving out into the floodplain.

In our example, the members of the fictional Bushwood Country Club have elected to construct a levee to protect their beloved homes.


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Although this levee is not in our DTM, we can incorporate the proposeelevation data into our GeoRAS model.

Make sure you are in Editing mode. Select “Create New Feature” f

d

or the Task and “Levees” as the Target. Digitize the levee line using the

Sketch tool to represent the high ground. The levee alignment on theBaxter River (Lower Reach) protecting Bushwood Estates is shown in Figure 8-31.

ood Estates.

Once the levee alignment is created, you need to assign elevations

Figure 8-31. Levee alignment for Bushw

along the levee. A contractor has provided the top-of-levee information and we can easily enter it using the (Levee Elevations) tool. Once the Levee Elevation tool is activated, click onthe levee line. In the dialog that appe

ars, the ground elevation will be

reported. You can override the elevation by entering a specified elevation. A feature class named “LeveePoints” is created and the

elevation are stored for each levee. and the levee point table is shown in

Figure 8-32. Enter elevations along the entire levee alignment.

distance along the levee line and The dialog for entering elevations


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Figure 8-32. Levee elevation points are entered using the Levee Elevation tool.

|

n

.

After the levee elevation data are entered, you must convert the levee from a 2D feature to a 3D feature (this is also required if you get the elevation data from the DTM). Select the RAS Geometry | LeveesLevee Completion menu item. The elevation data entered in the “LeveePoints” feature class is interpolated (no extrapolation) along the levee line and the data is converted to a 3D feature.

Select the Levees | Positions menu item to extract the levee positioand elevation at each cross-sectional cut line. A table named “LeveePositions” is created to store the data, as shown in Figure 8-33

line Structures

There are no inline structures in this example; however, they are treated similarly to the Bridge/Culvert feature class.

Figure 8-33. Levee position and elevation data extracted at cross sections.

In


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Lateral Structures

A lateral structure is used to represent a linear feature where flow wmove laterally over a weir between reaches or between a river reach and storage area. A lateral structure is used to represent the top of a levee or high ground that may be overtopped. In our example, we wincorporate two storage areas on the Lower Reach of the Baxter River that will require a lateral structure.

Make sure you are in Editing mode. Select “Create New Feature” fthe Task and “Lateral Structures” as the Target. Digitize the lateral structures in the downstream direction, using the Sketch tool, along the high ground. Cross-sectional cut lines should end at the lateral structures. Example lateral structures are shown in Figure 8-34.

ill

ill

or

Figure 8-34. Example lateral structures at the end of cross sections.

Attributes

After creating the lateral structure locations, you must assign a river and reach name to the structure and identify the cross section to connect the structure. Select the Lateral Structures | River/Reach Names and the Lateral Structures | Stationing menu items. The assignment of the river station is computed based on the shortest

st river reach. This process may not result in the desired river station – you

tion. If you started the weir just downstream of a cross section the distance to the upstream cross

distance from the upstream end of the structure to the neare

may need to modify the river station!

Next (while in Edit mode) you need to specify a weir top width and distance to the upstream cross sec


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section could be entered as zero. Example data for shown in Figure 8-35.

the lateral weirs is

dplain detention. A storage area a lateral structure and to another

nnection. We have two storage North side of the river and one on

“Create New Feature” for the Task and “StorageAreas” as the Target. Digitize polygons

areas using the Sketch tool. The storage le are shown in Figure 8-36.

Figure 8-35. Attribute information for lateral structures.

After the lateral structure information has been provided, you will needto convert the 2D feature class to a 3D feature class to extract the top-of-weir information. Select the RAS Geometry | Lateral Structures | Elevations menu item.

Storage Areas

Storage areas are used to model floois connected to a river reach by storage area by a storage area coareas in our example, one on the the South side of the river.

Make sure you are in Editing mode. Select

representing the storage areas used for this examp

Figure 8-36. Storage areas connect to the river reach by lateral structures.

After digitizing the storage areas, extract the elevation-volume daSelect the

ta. RAS Geometry | Storage Areas | Elevation Range


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menu item. This will identify the lowest and highest point within the storage areas and assign those attributes to the storage areas table under the names of MinElev and MaxElev. You can override the maximum elevation by entering an elevation in the UserElev field.

Next, extract the elevation-volume relationship by selecting the RAS Geometry | Storage Areas | Elevation-Volume Data menu item. Elevation-volume data will be written to a table named “ElevVol” for each storage area from the minimum to maximum elevation. The elevation interval is based on the elevation range divided by the “SliceCount” property (default is 10). Resultant elevation-volume data for the example storage areas is shown in Figure 8-37.

Figure 8-37. Elevation-volume data for storage areas.


There are no storage area connections in this example. Storage area connections would be created much like a lateral structure, though it would connect a storage area with another storage area rather than storage area to a river cross section.

Generating the RAS GIS Import File

Prior to writing the results to the RAS GIS Import File, you should verify that GeoRAS is aware of which data sets you want to export. Select the RAS Geometry | Layer Setup menu item. Click through

st for each Layer contains the

the tabs and verify that the dropdown liname of the correct data set. Screen shots for the Layer Setup for this example are shown in Figure 8-38 through Figure 8-41.


Figure 8-38. Layer Setup for geometric data extraction: Required Surface tab.

Figure 8-39. Layer Setup for geometric data extraction: Required Layers tab.

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8-28

Figure 8-40. Layer Setup for geometric data extraction: Optional Layers tab.

Figure 8-41. Layer Setup for geometric data extraction: Optional Tables tab.

After verifying the data that will be exported, select the RAS eometry | Extract GIS Data menu item. The dialog shown in

Figure 8-42 will be invoked allowing you to choose the destination irectory and filename.

G

d


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Figure 8-42. Filename and location for GIS export.

After pressing OK, GeoRAS will export the GIS data to an XML file and then convert the XML file to the SDF format. Two files will be created: “GIS2RAS.xml” and “GIS2RAS.RASImport.sdf”. This process will take several seconds. The dialog shown in Figure 8-43 will appear when the process has successfully created the files.

Figure 8-43. Successful GIS data export dialog.

ydraulic Analysis HEC-RAS H

ssion on using HEC-RAS software, modeling guidelines, HEC-RAS User’s Manual,

nual.

d save the project to the directory to which you want

Import the RAS GIS Import File

Open the Geometric Data Editor and select File | Import Geometry | GIS Format. Navigate to the RAS GIS Import File “BaxterRiver.RASImport.sdf” and select it. The data will be read into the data importer. Several tabs will provide you with import options.

HEC-RAS allows you to perform one-dimensional steady-flow and unsteady-flow analysis of river systems. The general steps in using HEC-RAS in concert with GeoRAS are discussed in this section. A complete discuand technical information can be found in the Applications Manual, and Hydraulic Technical Reference Ma

Start a New Project in HEC-RAS

Open HEC-RAS anthe HEC-RAS data files to be saved.


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The data set is in US Customary units so click on the Next button on the Intro tab (see Figure 8-44).

to

e Next button.

Figure 8-44. The first import option allows you to convert units.

The River Reach Stream Lines tab, shown in Figure 8-45, allows you choose which stream centerlines to import. Make sure that all streamlines are check and press th

Figure 8-45. Import options for river and reaches.

The Cross Sections and IB Nodes tab, shown in Figure 8-46, has the most options available. This is the window that will allow you to import various cross sections and their properties.


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Figure 8-46. Cross section and internal boundaries import options.

Go through each node and Turn Off the data import for all bridges (BR nodes). To do this select on the Bridge and Culvert node type, then uncheck the Import Data option, as shown in Figure 8-47. You are going to import them later.

gh the data

t the entire Import AS RS column by clicking in the header. Select the number of decimal places to be “0” and press the Round button. This will change the river stations to show the river stationing to the nearest foot. Press the Next button to continue.

Figure 8-47. You can access different node types, such as bridges, throuimporter.

Next, as shown in Figure 8-48, selec


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nnections options, shown in Figure 8-49. The two storage areas are checked. Press the

Figure 8-48. Import options allow you to change the cross section river stations.

The next tab brings you to the Storage Areas and Co

Finished –Import Data button to import the data.

Figure 8-49. Storage areas import options.

Once the data is imported, the Geometric Data editor schematic will show a georeferenced schematic of the river system, as illustrated in Figure 8-50. You will see the river network, cross sections, storage areas, and feature labels. Other display options are available from the View menu. Save the geometry.


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imported GIS data.

need to do is no obviously

data more closely by that the Manning’s

s are placed correctly, levees, ineffective areas, and blocked obstructions are placed correctly

Figure 8-50. Georeferenced HEC-RAS schematic generated from

After importing the geometric data, the first thing you perform a quality check on the data. Make sure there are erroneous or missing data. Next, look at your going though the plot of each cross section. Check n value data are reasonable, bank station

spatially and have the correct vertical component.

One of the best tools for visualizing and editing data is the Graphical Cross Section Editor. Select the Tools | Graphical Cross Section Edit menu item on the Geometric Data editor. The Graphical Cross Section Editor, shown in Figure 8-51, allows you to perform numerousediting tasks.

• Move the expanse of Manning’s n values.

• Move the location of bank station data.

• Add/move/delete ground points.

• Add/move/delete levees, ineffective areas, and blocked obstructions.

• Compare and merge cross section elevation data.


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Figure 8-51. Graphical cross section editor in HEC-RAS.

Cross Section Points Filter

Cross sections can have a maximum of 500 elevation points in HEC-RAS. This number is typically far more than you need to adequateldescribe the cross section, given the accuracy of the underlying terrain model. HEC-RAS has a cross section point filter that you can use to remove excess/duplicate points. Select the Tools | Cross Section Points Filter menu item.

In the points filter, select the Multiple Locations tab and Minimize Area Change tab, as shown in Figure 8-52. Next select All Riversfor the River option and press the arrow button. This will select all cross sections to filter. Enter 100 for the number of points to filter down to. In this example, note that most of the data has about 100 points, but some have almost 500. Press the Filter Points on Selected XS button.

y


8-35

Figure 8-52. Use the cross section points filter to remove redundant points.

erall ill report

few sections Single

oss section.

Points will be filtered to reduce (minimize) the impact to the ovarea of the cross section. The dialog shown in Figure 8-53 wthe results of the filtering when finished. Note that only a had significant point removal. You can click back on the Location tab to see the impact filtering had on any given cr

Figure 8-53. Results of the filtering process.


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Hydraulic Structure Data

Prior to looking at the lateral structures, modify the names of the storage areas. On the Geometric Schematic, select the Edit | Change

Name menu item. Click on the storage area and enter “Northside” and “Southside” for the respective storage areas, as shown in Figure8-54. After renaming the storage areas, uncheck the Change Name menu item.

Figure 8-54. Rename the storage areas with meaningful names.

At this point, the only hydraulic structures that have been imported are the lateral structures. You will need to complete the data for the lateral structures. Access the Lateral Structures editor shown in Figure 8-55. Select the Baxter River Lower Reach and make sure that the “North LS” is on the “Right Overbank” and the “South LS” is on the “Left Overbank”.

You will also need to connect the structures to the respective storage areas. Connect the lateral structure to a storage area by choosing the Set SA button in the Tailwater Connection frame. We will not be changing any of the other structure properties. After setting both storage areas, apply the data changes and save the geometry file.


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Figure 8-55. Lateral structures editor in HEC-RAS.

Now import a bridge and go through the typical steps for completing bridge data. Select the File | Save As menu item on the Geometric Data editor. Save the RAS geometry to a new name (like “GIS Import + Bridge”). Next, select the File | Import Geometry | GIS FormatNavigate to the RAS GIS Import File “BaxterRiver.RASImport.sdf” and select it. The data will be read into the data importer. This time you are ONLY importing 1 bridge!

On the River Reach Stream Lines tab unselect all of the river reaches, as shown in Figure 8-56, by clicking in the Import Stream Lines header and toggling the checkboxes off with the spacebar.

.

On the Cross Sections and IB Nodes tab make sure the Import River is set to All Rivers and uncheck the Import Data option for all river stations. Using the Round Selected RS option, round the river stations

Figure 8-56. Do not re-import the reach lines.


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to “0 decimal places” for All Rivers. Then check only the Bridges and Culverts node type. Next, place a check next to the bridge located

wn in on the Baxter River Lower Reach at river station 45360, as shoFigure 8-57. Make sure this is the only river station checked for import.

bridge just mation is not

terrain bridge deck on

t bank.

Figure 8-57. Import a single bridge using the GIS data importer.

On the Storage Areas and Connections tab, make sure no storage areas are checked for import. Press the Finished – Import Data button when ready. The single bridge will be imported into the HEC-RAS geometry. Save your geometry.

Access the Bridge/Culvert editor and select the “Railroad”imported. As shown in Figure 8-58, the bridge deck inforcomplete. This is because the bridge deck data was not in the model. You can see the approximate elevation of thethe left bank and the elevation it should tie into on the righ

Figure 8-58. Bridge deck information imported from GIS data will not be complete.


8-39

We will approximate the bridge as having an opening 1200 feet wide with bridge deck elevation of 83 feet and 5 feet deep. There are 12 piers, 10 feet wide, spaced at 100 foot intervals. Use the

bridge y the he final

deck/roadway editor and the Bridge Design editor to enter the information shown in Figure 8-59. You will also need to modifineffective areas on the cross sections bounding the bridge. Tbridge is shown in Figure 8-60.

Figure 8-59. Bridge deck and pier information.

Figure 8-60. Completed bridge information.


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You may continue by importing additional bridges and completing tdata. You will also need to set the Bridge Modeling Approach for each bridge and adjust other parameters.

After the bridge data has been entered, revisit the ineffective flow area data and adjust the spatial location and elevations aroun

he

d bridges. You will also need to go through each blocked obstruction and raise

veloping an unsteady-flow model, however, you should always put together a steady-flow model to evaluate the river

e of ve name for each

profile by selecting the Options | Edit Profile Names menu item. ition (use y to the

Options |

the elevation to the height of the building it is representing.

Flow Data and Boundary Conditions

For this example, we are going to put together an unsteady-flow model. When de

system under a range of flows.

Steady Flow

Enter multiple profiles to cover the range of flows the unsteady-flow model will experience. In this example, enter 3 steady flow profiles (though typically you would enter many profiles to cover the rangflows), as shown in Figure 8-61. Enter a descripti

You will also need to set the downstream boundary condNormal Depth Slope = 0.001) using the Reach BoundarConditions button. Set the initial storage area elevationsminimum elevation of each storage area by selecting theSet Storage Area Elevations menu item.

Figure 8-61. Steady flow and boundary conditions data editor.


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Access the Steady Flow Analysis window and press the Compute button to calculate water surface profiles for the three flows. HEC-RAS will perform checks on your data. If you did not enter all the requiredata for performing a steady-flow run, HEC-RAS will not compute and will give you an error message to fix your data.

d

After successful simulation, you should go through the RAS output and

need

upstream and downstream of the bridge becomes effective at the same time.

ding polygon information, using the

t If

rtopped, you expect the bounding polygon to follow the

verify the results. The Profile Plot and Cross Section Plots are very effective tools for identifying problem areas. Most likely, you willto adjust ineffective areas around bridges so that the conveyance

The last item to verify is the bounGIS Tools | Plot GIS Profile Reach Bounds tool. You want to makesure that the HEC-RAS results will produce an appropriate floodplain inthe GIS. For this example, we have a levee on the North side of the Lower Reach. If the levee is overtopped, you expect the bounding polygon to go to the edge of the cross section – and you would wanall of the levees in the surrounding area to be overtopped together. it is not oveedge of the levee as is illustrated in Figure 8-62.

Figure 8-62. Examine the bounding polygon for each water surface profile.

After verifying the RAS results, you would export the water surfaceprofile results to the GIS and perform floodplain delineation with GeoRAS. You would then examine the floodplain boundary and identify how you could improve the river hydraulics model. The floodplain mapping step is discussed later in this section.


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Unsteady Flow

Unsteady-flow modeling is more complicated than steady-flow o .

For unsteady-flow modeling, you will need to examine the hydraulic properties tables for each cross section and each bridge. You want to

aulic properties and you want the of expected flows. HEC-RAS will

s

You will need to enter hydrographs, boundary conditions and initial

modeling. You should always put together a steady-flow analysis tiron out issues with your model prior to modeling in unsteady flow

avoid having abrupt changes in hydrproperties to cover the entire range come up with default parameters for building hydraulic property tablefor cross sections, but for bridges (at a minimum) you will need to specify a maximum head water ele tion. The hydraulic table properties are accessed from the Cross Section editor and Bridge editor from the HTab button.

va

conditions through the Unsteady Flow editor, shown in Figure 8-63. For this example, use an inflow hydrograph for the Baxter River that has a baseflow of about 2,000 cfs and peak of about 150,000 cfs (see Figure 8-64). The inflow hydrograph for Tule Creek has a baseflow ofabout 2,000 cfs and peak of about 10,000 cfs.

Figure 8-63. Unsteady Flow data editor in HEC-RAS.

Initial conditions were set for the Baxter River and Tule Crshown in Figure 8-65. Note that you must set an initial st

eeka

as ge for the


8-43

storage areas. The initial elevations for the storage areas were set to make them “dry” at the start of the simulation.

Figure 8-64. Example inflow hydrograph for the Baxter River.

Figure 8-65. Unsteady flow boundary conditions.


8-44

Once the geometry and flow data has been entered (checked and refined) you are ready to simulate. Open the Unsteady Flow Analysiswindow and create a new plan. to compute detailed velocities, selethe Options | Flow Distribution Locations menu item. In the dialthat appears, select the Global Subsections for th

ct og

e left overbank, main channel, and right overbank, as shown in Figure 8-66.

Detailed velocity output easily selected for all cross sections using the Global

Subsections option.

e programs to run: Geometry Preprocessor, Unsteady Flow Simulation and Post Processor. Establish a

le – here we have selected

a 10-minute time step. Your Unsteady Flow Analysis window should Compute

Figure 8-66.

Next, check on the thre

Simulation Time Window and select the Computation Settings. You will need to select an appropriate Computation Interval based on cross section shape, spacing, and hydrograph characteristics. This exampis not very sensitive to the time step selected

look similar to that shown in Figure 8-67. Press the button to perform the unsteady flow simulation.

Figure 8-67. Unsteady Flow Analysis window for HEC-RAS.


8-45

Assuming the program successfully runs to completion, you will need to review the detailed model output and assess how you can improve your model. Model refinement may require getting more data from

may need to modify the olerances to

model results, ed with the

nundation mapping.

File | Export GIS The dialog shown

he profiles of

ll of

the GIS or adjusting model parameters. You initial conditions, computation interval, or program tcreate a stable RAS model.

After reviewing all the data, simulate again. Reviewrefine the model, and simulate. Once you are satisfihydraulic model, export the results to the GIS for i

Export the HEC-RAS Results

Open the “Steady Flow” HEC-RAS plan. Select the Data menu item from the main HEC-RAS window. in Figure 8-68 will be invoked allowing you to select tinterest to export. For steady flow, you will have three profiles to choose from, while for unsteady flow you would have many profile choices.

Enter the filename and directory to store the RAS GIS Export File (RASExport.sdf). It will default to the directory where your project isstored. Press the Select Profiles to Export button and select athe profiles. Also, turn on the Velocity Distribution export option.

Press the Export Data button to generate the export file.

Figure 8-68. HEC-RAS GIS Export dialog.


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RAS Mapping

The mapping of HEC-RAS results occurs with two basic tasks: (1) import the HEC-RAS results to the GIS as feature classes and (2) perform the mapping analysis.

Import the RAS GIS Export File

You must convert the SDF file exported from RAS to an XML format

that GeoRAS can read. Press the (Convert SDF to XML) button on the GeoRAS toolbar. The dialog shown in Figure 8-69 will allow you to select the RAS GIS Export File (SDF) and will convert it to an XML file. The same filename and directory are used to store the new file.

ess ialog, shown in Figure 8-70.

Figure 8-69. RAS SDF conversion to XML dialog.

Next, select the RAS Mapping | Layer Setup menu item to accthe Layer Setup d

Figure 8-70. Layer Setup dialog for processing HEC-RAS results in GeoRAS.


8-47

Enter a New Analysis name “Steady” and select the RASExport.xml

After the import of the data is complete, examine the bounding

g

file to read. Verify the Terrain model and select the directory to store results. The name of the Analysis will be appended to the directory you choose. Enter a Rasterization Cell Size (here we’ve used 20) for the resultant inundation depth grid (you may need to refine the grid-cell size to improve the floodplain delineation). Press OK to dismiss the layer setup. A new map called “Steady” will be created and the terrain model will be loaded.

Select the RAS Mapping | Read RAS GIS Import File menu item. This process will take a few minutes as the HEC-RAS results are imported into feature classes and the terrain TIN is converted to a GRID. There will be a feature class created for cut lines, bounding polygon information, and storage areas. The cut line feature class (“XS Cut Lines”) will hold the cross section locations attributed with a water surface elevation for each cross section for each profile. The bounding polygon layer (“Bounding Polygon”) will have a bounding polygon feature for each water surface profile. Point feature classes will be created for the velocities (“Velocities”) and bank point locations (“BankPoints”). The storage area layer (“Storage Areas”) will have a feature for each storage area and be attributed with a water surface elevation for each profile.

polygon for the “Biggest” event (or P003 as it appears in the attribute table) that was imported to the GIS. This polygon will limit the extents of the inundation mapping. Is the bounding polygon consistent with the RAS model and will it allow the appropriate floodplain delineation? One specific place to check is at the levee. As illustrated in Figure 8-71, the bounding polygon follows the levee until it is overtopped. Downstream of the overtopped levee the boundinpolygon is out at the edge of the cross sections. This is consistent with the RAS model, but will significant backwater result behind the levee? In this case, no, there is high ground upstream of the overtopped area.

Figure 8-71. Examine the bounding polygon for consistency prior to floodplain delineation.


8-48

After the feature classes are created and added to the map, the DTM will also be converted to a raster data set. The grid-cell size will be determined by the Rasterization Cell Size entered during the layer setup process. The raster copy of the terrain model will be named “DTMGRID” and stored in the Analysis directory.

Inundation Mapping

Inundation mapping is performed in two basic steps. First a water surface TIN is constructed from the cross sections and water surface elevations. In the next step, the water surface TIN is compared with the DTM.

Water Surface TIN

Select the RAS Mapping | Inundation Mapping | Water Surface Generation menu item. The dialog shown in Figure 8-72 will allow you to pick the water surface profile to process. For this example, choose the “Biggest” profile and press OK.

Figure 8-72. Water surface profile selection dialog for building water surface TINs.

The water surface TIN will be created and added to the analysis map with the name “t Biggest”. The TIN will be saved to disk in the Analysis directory as “tP003”. The water surface TIN will include a

in re

o process. By default, the “Smooth Floodplain Delineation” option is selected – if you want the floodplain boundary to precisely follow the depth grid, uncheck the smoothing option. Choose the “Biggest” profile and press

surface outside the area of interest. This non-modeled area will be removed during the delineation process with the bounding polygon.

Floodplain Delineation

Select the RAS Mapping | Inundation Mapping | FloodplaDelineation Using Rasters menu item. The dialog shown in Figu8-73 will allow you to pick the water surface profile t


8-49

OK. Watch the Status Bar (at the bottom of the ArcMap window) for status messages and completion percentage.

Figure 8-73. Water surface profile selection dialog for performing floodplain delineation.

The water surface TIN will be converted to a GRID based on the Rasterization Cell Size. It is then compared with the raster DTM to

difference within the bounding polygon. Water vations greater than the terrain elevation are included in

the inundation depth grid. The Storage Areas layer will also be converted to a GRID and flood depths will be added to the depth grid.

d Biggest” and the floodplain boundary will be added with the “dP003” in the

ored in the output

” profile (for a rst thing you

ctions are wide enough important at the

compute the elevation surface ele

The inundation depth grid is then converted to a vector data set defining the floodplain boundary. When the delineation is complete, new layers will be added to the map and a dialog will be invoked updating you that the “Floodplain mapping completed successfully!”

The inundation depth grid will be added to the analysis map with the name “name “b Biggest”. The depth grid is stored on disk as Analysis directory while the floodplain boundary is stgeodatabase as “bP003”.

The resulting floodplain delineation for the “Biggestportion of the model) is shown in Figure 8-74. The fishould verify is that the extent of the cross seto allow for floodplain delineation. This is especiallyoutside portion of bends in the river.


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The other areas to look at are the a few areas of dry land (islands)

Figure 8-74. Initial floodplain delineation overlaying contours and cut lines.

Note that the floodplain delineation resulted in some interesting features identified by the arrows in Figure 8-74. One prominent feature is the disconnected water body on the south-east side of the river. We must consider whether this is appropriate and makes hydraulic sense.

It can be determined whether the disconnected “pond” should be included in the delineation by looking a the cross section plot in HEC-RAS (you can use the GIS to identify the river station). A quick look atthe cross section plot indicates that the area should not be wet. You should go back to the RAS model and add a levee to the high ground to keep water from flowing out into the left bank (or edit the floodplain polygon manually). The cross section without the levee is shown in Figure 8-75. In addition, the levee option should be used on the next cross section downstream.

near the storage area locations. Cursory review of the dry land indicates that it is indeed high ground.


8-51

Figure 8-75. HEC-RAS cross section shows flooding in the left overbank that should be

e option.

Another set of areas to consider are the slender regions at the end of the cross sections where storage areas are used. These areas are not

ge area through a culvert or gate – so the high ground would not be inundated. In this example, however, the high ground separating the

he storage area should be inundated. You should diting the Storage Areas in HEC-RAS (Edit | Move

Object menu item) so that future delineations are correct. The next ortant

d

limited using the leve

inundated because the cross sections and the storage areas did not properly overlap and a gap was left between the features. The areaadjacent to a storage area may not be wet because it could be a high linear feature like a road or levee and water is passed to the stora

cross sections and tfix this issue by e

floodplain delineation iteration is shown in Figure 8-76. It is impto note that edits made within the HEC-RAS model have longevity anwill propagate through to future floodplain delineations, whereas edits made within the GIS are more singular events.


8-52

e ll

rther, it oodplain

ck up behind

n more insight

at requires several iterations between HEC-RAS and the GIS to arrive at results that are hydraulically correct. We will neglect further

u will want to zoom in along the edge of the floodplain and determine whether the grid-cell size used is small enough to

Figure 8-76. Final floodplain delineation overlaying contours and cutlines.

There are still several areas we would want to investigate for thcorrectness in the floodplain delineation. There are still several smaislands in the floodplain and disconnected ponds of water. Fuappears that the bounding polygon has removed part of the flon the north side of the river (behind the levee). Perhaps, if the levee was overtopped farther downstream, water would flow bathe levee. You would need to revisit the hydraulics model and identify how you should adjust your cross sections and options to best represent the flow situation.

You could continue the investigation by zooming into areas and comparing the floodplain with the terrain model to gaiinto correcting the river hydraulics model. This is a looped process th

model refinement in this example.

Next, use the depth grid to evaluate the floodplain. Using the depth grid with a color gradient will quickly allow you to identify areas flooded to greater (or lesser) depth. The Identify tool can be used to find water depths at various locations, as shown in Figure 8-77. Further, yo

accurately delineate the floodplain. The 20ft cell size used in this example may not be appropriate for other studies.


Figure 8-77. Inundation depths are easily identified in the GIS.

Velocity Mapping

Velocity mapping is completed by interpolating detailed velocity information between cross section. In order to perform the velocity mapping, the floodplain boundary for the profile of interest must exist.

Select the RAS Mapping | Velocity Mapping menu item and choose the profile of interest (“Biggest”) for interpolation, as shown in Figure 8-78.

igure 8-78. Select the profile of interest to perform velocity interpolation.

The floodplain boundary, velocities, and bank station data are used to interpolate velocities between cross sections. During interpolation, a dialog will provide status updates as to the progress, as shown in Figure 8-79.

F

8-53


8-54

Figure 8-79. Interpolation status is updated during the computations.

After the interpolation is complete, the velocity grid is added to the Map. As shown in Figure 8-80, the velocities transition between the cross sections in the channel and floodplain, but the velocity is zero in the storage areas.

Figure 8-80. Interpolated velocities export from HEC-RAS.

Using the point velocity data on top of the interpolated surface can also be helpful in determining model deficiencies. In Figure 8-81, for instance it is clear that the spit of water on the north side of the river should be an area of zero velocity. The HEC-RAS model should be refined to reflect this using an ineffective flow area.


8-55

Shear Stre

ress mapping is performed in the identical manner as velocity , except you must select the “Shear Stress” output option

Export File in RAS and selecting the RAS item in HEC-GeoRAS.

Strea

ream Power mapping is performed in the identical manner as velocity mapping, except you must select the “Shear Stress” output

ing the RAS GIS Export File in RAS and selecting the am Power Mapping menu item in HEC-GeoRAS.

Figure 8-81. Interpolated velocity surface overlaid with point velocity data.

ss Mapping

Shear stmappingwhen creating the RAS GIS Mapping | Shear Stress Mapping menu

m Power Mapping

St

option when creatRAS Mapping | Stre


8-56

Ice Thickne

re 8-82. This fictitious model demonstrates the capability of RAS to calculate ice thickness in a cross section due to an ice jam at

ss Mapping

In order to perform the ice mapping portion of this example, you needto export the results for the “Ice Jam” plan in the HEC-RAS model, as shown in Figu

a bridge.

Figure 8-82. Export HEC-RAS results for ice thickness information.

Convert the RASExport.sdf file to XML, perform the RAS Mapping LayerSetup, an

d import the RAS results. Note that this time, a point feature

class (“IceThickness”) has been created with ice thickness information for some of the cross sections. As with the velocity analysis, perform

ilable profile (“Biggest”). Once ou are ready to perform the ice

mapping.

on, as shown in Figure 8-83.

the floodplain delineation for the avathe floodplain has been delineated, y

Select the RAS Mapping | Ice Mapping menu item. The standard profile selection dialog will allow you to pick the profile to perform the ice interpolation


8-57

Figure 8-83. Water surface profile selection dialog for ice interpolation.

pdates. After the o the map.

After selecting a profile and pressing the OK button, the interpolation status window will appear providing progress uinterpolation is complete, the ice thickness grid is added tObserve the distinct change in ice values at the bridge, as shown in Figure 8-84, indicative of an ice jam situation.

m Figure 8-84. Display of interpolated ice thickness data at an ice ja

.

Chapter 9 Example – Multiple DTMs

9-1

C H A P

etwork (TIN) is an e definition may be

plex areas (such as the channel) can have an increased concentration of elevation data. You

unmanageable to work with in the ArcGIS environment. If this is the ase, HEC-GeoRAS provides the functionality to use multiple terrain

Start a Ge

T E R 9

Example – Multiple DTMs

Representing terrain with a triangulated irregular nefficient method of modeling. Areas requiring littlrepresented by a few data points while com

can represent a very large area using the TIN model representation bygathering and using a minimum of data points. A gridded representation of a similar terrain surface, however, may require many, many more data points resulting in a very large data set.

Very large terrain models may result in data sets that are

cmodels rat e model. This chapter will demonst errain models using the Wailupe

and data layers.

Tasks •

• Class

• Extrac

•

T e either ich you want to ready been

Chapter 4) an her

e polygon ngle DTM

her than the single largrate the use of multiple t

River and floodplain terrain model

Start a GeoRAS project

Create the Terrain Tiles Feature

t Cross Sections

Inundation Mapping

oRAS project

utilize multiple terrain models, you multiple terrain tiles or a single terrain

create smaller models. The Wailupe Ridivided into three DTMs (using the

o st already havmu model from wh

ver DTM has alprocess discussed in

d we will use them as the basis of the terrain. The otrequirement is to have a polygon feature class that represents the bounds of each DTM to use for each cross section. Thfeature class is the only thing that is differs from the siprocesses discussed in this document.

Chapter 9 – Multiple DTMs

9-2

Start by opening ArcMap and loading the 3D Analyst, Spatial Analyst and HEC-GeoRAS extensions. Save the project. Add a new map using the ApUtilities | Add Map menu item and name it “Geometry”.

We will first load the terrain models. For this example, we have three TINs called “Upper”, “Middle”, and “Lower” representing the Wailupe River watershed. Load the terrain models and verify that they overlap each other.

so t

GeoRAS to the location of the TINs.

load the feature classes from the “TerrainTiles” geodatabase. features are the only necessary feature

classes because we completed the attribute data during the “Data

Verify that each cut line lies completely within one of the three terrain

Create the

You can create a polygon feature class for the Terrain Tiles layer directly in GeoRAS using the RAS Geometry | Terrain Tiles menu item. Provide a name for the feature class, as shown in Figure 9-1, and press OK.

Making sure that the terrain models overlap is extremely importantthat the triangulation in the transition zones from one TIN to the nexis done correctly. GeoRAS doesn’t actually require that the TINs are loaded, the polygon feature class will have pathnames directing

Next,The “River” and “XSCutLines”

Import” example, but if you plan on adjusting cut line locations you will want to add the bank lines and flow path lines.

models.

Terrain Tiles Feature Class


9-3

Figure 9-1. Creating a new feature class in GeoRAS.

Start editing the new “TerrainTiles” feature class and choose “New Feature” as the Task and “TerrainTiles” as the Targetshown in Figure 9-2. Select the Sketch tool and draw thethe “Upper” TIN.

Create , as

bounds of

gure 9-3.

re that th the

Figure 9-2. Editor options when adding polygon features.

An example of the bounds for the “Upper” TIN is shown in FiNote that in creating the polygon, we are really just considering the bounds of the cross-sectional cut line. You want to make sueach cut line is completely with the polygon and completely wibounds of the terrain model that the polygon is representing!

Figure 9-3. Polygon feature for the Upper TIN.


9-4

Next, enter attribute information for the polygon. The HydroID information will be automatically populated as you create each polygfeature by GeoRAS (which has the ApUtilities menu loaded). You will have to enter the name of the terrain model (TileName), the path to the loc

on

ation on disk (TileDirectory) and the type of terrain (TerrainType) in the attribute table, as shown in Figure 9-4.

Figure 9-4. Attributes for the polygon representing the Upper TIN.

After entering the attribute information for the first polygon, create a second polygon for the “Middle” TIN. Enter the attribute information for the section polygon.

The polygons must be edge matched. During the digitizing process, just make sure that the new polygon overlaps the old polygon. To edge match the two polygons, select the polygon for the “Upper” TIN, as shown in Figure 9-5.

Figure 9-5. Polygons (a) overlapping and (b) edge matched and have no cross sections overlapping polygons.

Next select the Editor | Clip menu item. The dialog shown in Figure 9-6 will be invoked allowing you to choose a Buffer Distance and clipping option. Choose a zero buffer distance and to discard the intersecting area.

a) b)


9-5

Figure 9-6. Clipping options available from the Editor.

the overlapping area for the “lower” terrain model. Verify that each .

daries will look like that illustrated in Figure 9-7 and the attribute table should look similar to that shown in Figure 9-8.

Repeat the process of digitizing a polygon boundary and clipping out

cross section feature falls within a polygon and the associated TINUpon final inspection, the polygon’s boundaries and approximate DTM boun

Figure 9-7. DTM and Polygon bounds for multiple terrain models.

Approximate DTM Boundary

Polygon Feature


9-6

Figure 9-8. Attribute data for the polygon feature class for using multiple terrain models.

Extract Cross Sections

Prior to extracting the cross-section data, verify that the attribute information is correct for the river stations, bank locations, and reach lengths. If you modified the layout of any cross section, you will need to re-attribute the cut lines with updated information.

After updating the attributes, elevation data is extracted. The data extraction process will appear to work the same way as with a single terrain model. GeoRAS does it the same way, it just needs to load each terrain model one at a time and will do so in sequence using the name and directory path specified in the polygon feature class.

Extract RAS Layers

Elevation information for the other RAS Layers can be done using multiple feature classes. The rules for the other feature classes are the same as those for the cross sections – the entire feature must lie within one terrain model and may not overlap multiple terrain models!

RAS Mapping

You can import the data extracted in HEC-RAS, complete the model, simulate, and export the results to the GIS, or use the RAS GIS Export File provided.

In ArcMap, select the RAS Mapping | Layer Setup menu item. Specify a name (“Delineation”, for example) for the New Analysis and select the “Wailupe.RASExport.xml” file. Next specify Multiple for the terrain analysis and select the “TerrainPolygons” layer. Lastly, specify the Output Directory and Rasterization Cell Size. The parameters for the Layer Setup are shown in Figure 9-9.


9-7

rform e as

elineation. The

terrain grids will be named based on the HydroID for the polygon

Figure 9-9. Layer setup parameters for floodplain delineation.

Go through each of the Inundation Mapping menu items to pethe floodplain delineation. Note that the process works the samfor a single terrain model. The only difference is the polygon feature class for the terrain tiles is loaded to the map and a grid is created foreach terrain model for performing the floodplain d

feature prefixed by “grd”. The data generated by the floodplain delineation process in shown in Figure 9-10.

ocess. Figure 9-10. Data created during the floodplain delineation pr


9-8

During the Waspecific profile

ter Surface TIN process a single TIN is created for a . The water surface TIN is then used to perform the

floodplain delineation process for each terrain model. The result from e each terrain tile is then merged to create one floodplain for the entir

area.

Appendix A References

A-1

A P P E N D I X A

Referen

Env

Hydrologic Engineering Center (1995). Flow Transitions in Bridge , RD-42, U.S. Army Corps of Engineers, Davis, CA.

Hydrologic Engineering Center (2009). HEC-RAS (Version 4.1), River Davis,

Hyd

gineers, Davis, CA.

Hyd

Hyd r s of

ces

ironmental Systems Research Institute (2000). Using ArcMap, Environmental Research Institute, Inc., Redlands, CA

Backwater Analysis

Analysis System, User’s Manual, U.S. Army Corps of Engineers, CA.

rologic Engineering Center (2009). HEC-RAS (Version 4.1), RiverAnalysis System, Hydraulic Technical Reference Manual, U.S. Army Corps of En

rologic Engineering Center (2009). HEC-RAS (Version 4.1), River Analysis System, Applications Manual, U.S. Army Corps of Engineers, Davis, CA.

rologic Engineering Center (2002). HEC-GeoRAS, An extension fosupport of HEC-RAS using ArcView, User’s Manual, U.S. Army CorpEngineers, Davis, CA.

Appendix B HEC-RAS Data Exchange

B-1

A P P E N D

HEC-RA

mponent to the This or

-

one per bank), ineffective flow area positions and elevations, and s.

• Bridge deck information for top-of-weir profile, deck width, and istance to m ection.

eral and ructu deck width, and distance to the upstream cross section for inline structures.

Storage area elevation-v

• Storage area connection information, top-of-weir profile, width,

port o nclude:

and elevation data.

• Water surface elevations at each cross section.

ding poly informat

oss-sect opertie

ity in at a

• Ice thickne rmation ss section.

I X B

S Data Exchange

At Version 2.0, HEC-RAS introduced a geospatial cogeometry for the description of river networks and cross sections. capability makes it possible to import channel geometry from CADDGIS programs though automated data extraction procedures. Similarly, water surface elevations and other HEC-RAS results can beexported to CADD and GIS where they can be used to create water surfaces for inundation mapping.

The spatial data that HEC-RAS can import and export are evolving each new version of the software results in additional capabilities. HEC-RAS Version 4.0 will import and export data using a spatial data format in an ASCII text file.

Data import options include:

• The structure of the river network, as represented by a series of interconnected reaches.

• The location and geometric description of cross sections for elevation data, bank positions, downstream reach lengths, Manning’s n values data, levee positions and elevations (limited to

blocked obstruction positions and elevation

d the upstrea cross s

• Lat inline st re information, top-of-weir profile,

• olume information.

and storage areas connected.

Data ex ptions i

• Cross section locations

• Boun gon ion for each water surface profile.

• Cr ional pr s.

• Veloc formation

ss info

cross section.

at a cro


B-2

Spatial Da

d ords,

This file format is evolving in that additional data types will be

d of records, which are composed f keywords and values. All records must begin with a keyword. A

he keyword. Spaces, tabs, or line ends can be used as delimiters within a

rd.

at co a keyw or end of a group of related records. For example, the record “BEGIN HEADER:” mark eginninrecord that contains a keyword and a value assigns that value to the

Keywords

ords are u dentifymodel being named by the ke . Keywords must end

a colon sep g the k will have the spaces removed up letters capitalized. The keywords “Begin Header:”, “Begin header:”, and “Be GiNH eadEr:”

ll equivalen adabwill contain internal spaces.

Values

ble or multiple an array es can be in t numbers, gs, or s (X, Y in an array of

lled ment”

A numerical value cannot c nt number can contain a decimal point; an integer cannot. Elements in an array can be separated by commas, blanks, tabs, or line ends.

ta Format

HEC-RAS Version 4.0 will import and export data using a formatteASCII text file. In general, the spatial data format consists of reckeywords and values. This section provides the general rules for constructing the HEC-RAS import and export file.

added and existing ones may be modified for future versions. If you are writing software to read and write to the HEC-RAS spatial data format, keep in mind that you may need to modify your software to remain compatible with future versions of HEC-RAS.

Records

The spatial data format is composeorecord can also contain a value or a set of values following t

reco

A record th ntains ord and no value marks the beginning

s the b g of the header section of the file. A

part of the model being named by the keyword.

Keyw sed to i that values unique to the part of the yword will follow

with aratin eyword and the values. All keywords to the colon and the

are a t. For re ility, keywords named in this document

A record can assign a single value to a single variavalues intext strin

. Valulocation

tegers, floating poin, Z, label). A single value

values is ca an “ele of that array.

ontain internal blanks. A floating poi


B-3

A text string can contain internal blanks, tabs, and commas, but cannot contain i

cons three clabel). The first two coordina The coordinate values are flo and the label can be any type of value. In certain cont

ot be requ If a labmust be given; the value of “ rdinate only. The coordinate values a e separated by commas, blanks, or tabs, but a location cannot contain internal line

roups

Records in the data file can b es of groups: objects and file sections. An e to describe an entity within the model – a cross section, for example.

e section is a logical or fur, for example, is a sec

entire file.

ile sectno fi

a keyword composed of the word on colon and ends with a keyword composed of the word

ND” followed by the section name and a colon. For example, records containing only the keywords “BEGIN HEADER:” and “END HEADER:” are used to start and end the header section of a file. An object starts with a record containing a keyword naming an object type and “END:” only. For example, a cross-section object with the record containing the keywords “CROSS-SECTION:” and ends with the keyword “END:” only.

Comments

Hash characters (#) are used to identify comments. When a hash character is encountered in the file all data from the hash to the next line end is ignored. A line that begins with a hash is equivalent to a blank line.

RAS GIS Import File (RASImport.sdf)

HEC-RAS reads channel geometry from a text file composed of several sections. A discussion of the sections in the import file is provided. And example RAS GIS Import File is provided at the end of this appendix.

nternal line ends.

A location ists of oordinate values and a label (X, Y, Z, tes are planar and the third is elevation. ating point numbers

exts, the elevation value or the label may n ired. el is used, all three coordinate values

NULL” is valid for the elevation coond the label can b

ends.

Data G

e collected in two typobject is a group of records that combin

A filheade

nctional grouping of data. The file tion that contains a description of the

Objects and fkeywords but

ions begin values. A

and end with records that contain le section starts with a record containing

“BEGIN” followed by the sectiname and a“E


B-4

Header

GIN HEADER:” and “END HEADER:” and should contain a record to identify the units system

able B-1. Header options for the spatial data file.

Keyword Value Type Value

The header is bounded by the records “BE

used in the imported data set. The units system can be “US CUSTOMARY” or “METRIC”. A summary of records that may be used in the Header section are provided in Table B-1.

T

UNITS: String US CUSTOMARY or METRIC

DTM TYPE: String Type of terrain model (TIN or GRID)

DTM: String Name of terrain model

STREAM LAYER: String the CADD or GIS.

NUMBER OF REACHES: er

CROSS-SECTION LAYER: String Name of the Cross-Sectional Cut Lines IS.

teger Number of cross sections in the SDF file.

.g. lane)

DATUM: String

TUM:

ENT:

Xmin: Float Minimum easting of geospatial data.

loat Minimum northing of geospatial data.

data.

END SPATIAL EXTENT: None

PROFILES:

g array

Name of Stream Centerline layer used in

Integ Number of reaches in the SDF file.

layer used in the CADD or G

NUMBER OF CROSS-SECTIONS:

In

MAP PROJECTION: String Projection (coordinate) system used (eStatep

PROJECTION ZONE: String Projection zone (if applicable, e.g. 5101)

Reference datum for planar coordinates.

VERTICAL DA String Reference datum for vertical coordinates.

BEGIN SPATIAL EXT None None. Begin of Spatial Extents object.

Ymin: F

Xmax: Float Maximum easting of geospatial data.

Ymax: Float Maximum northing of geospatial

None. End of Spatial Extents object.

NUMBER OF Integer Number of profile exported from HEC-RAS. RAS GIS Export File only.

PROFILE NAMES: Strin Water surface profile names exported from HEC-RAS. RAS GIS Export File only.


B-5

River Network

The river network section is bounded by the records “BEGIN STREAMNETWORK:” and “END STREAM NETWORK:” and contains records describing reaches and reach endpoints. At a minimum, the stream network section must contain at least two endpoints and one reach.

A reach endpoint is represented by a r

ecord containing the keyword “ENDPOINT:” followed by four comma-delimited values containing the

object that begins with a record ontaining only the keyword “REACH:” and ends with a record only

ach object must ID, a FROM

t, and a TO p h M and TO point IDs must match endpoints l

also in an arrcenterline. This array begins with a record containing only the keyword "CENTE :" and e ed. A location element in the array contains the X, Y, and Z coordinates of

ver station. In HEC-RAS, elevation and stationing are optional in the stream network

on. If a lo elemen occupy the fourth field in the e

oning is use dexing l used to precisely locate objects in th of records that may be used in the River Network section are provided in Table B-2.

Table B-2. River network options for the spatial data file.

Keyword Value pe Va

endpoint’s X, Y, Z coordinates and an integer ID.

A reach consists of a multi-recordccontaining the keyword “END:”. At a minimum, a recontain records setting values for a Stream ID, a Reach poinIDs for

oint. A reacisted before the

’s FRO reach object in the file. The reach

object must conta ay of locations defining the stream

RLINE nds when any keyword is encounter

a point on the stream centerline, and the point’s ri

definiti cation t includes a station value, it mustlement.

Stati d for in ocations along reaches, and is not e model. A summary

Ty lue

ENDPOINT: Lo X, cation Y, Z coordinates and integer ID.

REACH: None Marks beginning of Reach object.

The following records are required for a Reach object.

STREAM ID: String River identifier to include reach.

REACH ID: String Unique ID for reach within river.

FROM POINT: String Integer reference to upstream endpoint.

TO PO Integer reference to downstream endpoint.

CENTERLINE: Location Array elements contain coordinates and station

END: None Marks end of Reach object.

INT: String

array values.


B-6

Cross Sections

The cross-sectional data section begins with a record containing only the keyword "BEGIN CROSS-SECTIONS:" and ends with a record containing only the keyword "END CROSS-SECTIONS:". A cross

ord containing only the keyword "END:."

fying the Stream , a 2D cut line, and

ries of 3D loc e ection. Stationing is given in miles for data sets with plane units of feet and in kilometers for data

u meters."CUT LINE:" followed by an array of 2D locations. A cross-sectional polyline consists label "Swritten as comma-delimited X, Y, Z real-number triples, one triple to a

River Network section are provided in Table B-3.

Table B-3. Cross-sectional data section l data format.

V ype V

section is represented by multi-record object beginning with a record containing only the keyword "CROSS-SECTION:" and ending with a rec

A cross-sectional object must include records identiID, Reach ID, and Station value of the cross-sectiona se ations on th cross s

sets with plane nits of A cut line is composed of the label

of the URFACE LINE:" plus 3D coordinates

line. A summary of records that may be used in the

options for the spatia

Keyword alue T alue

CROSS-SECTION: N Mone arks beginning of Cross Section object.

END: None Marks end of a Cross Section object.

The following records are d for a C

S Idse

Fl The rel on al

L n a

A ar coordinates of cr

SURFACE LINE: Location array

Array elements contain 3D coordinates of cross section.

The fol nal for a Cross Section object.

NODE

BANK

require ross Section object.

STREAM ID: tring entifier for the River on which the cross ction resides.

REACH ID: String Identifier for the Reach on which the cross section resides.

STATION: oat ative position of the cross sectiong the river reach.

CUT LINE: ocatiorray

rray elements contain planoss section strike line.

lowing records are optio

NAME: String Description of cross section.

POSITIONS: Float Fraction of length along cut line where mainchannel bank stations are located. (Left, Right)


B-7


REACH LENGTHS: Float Distance along left overbank, main channel and right overbank flow paths to next cross

(Left, Channel, Right) section downstream.

N VALUES: Float Manning’s n values and fractional distance al(fraction, n value)

POSITIONS: S Float Lecut line and elevation.

S oat Ineffectialwi . (ID, begin fraction, end fraction, elevation)

BLOCKED POSITIONS:

Float Bl xpressed as a fraction along cut line to beginning and end positions wi(I end fraction, elevation)

VATION: F WH only.

ong the cut line to start of n value.

LEVEE tring, vee positions expressed as a fraction along

(ID, fraction, elevation)

INEFFECTIVE POSITIONS:

tring, Fl ve flow areas expressed as a fraction ong cut line to beginning and end positions th trigger elevation

ocked flow areas e

th trigger elevation. D, begin fraction,

WATER ELE loat array ater surface profile names exported from EC-RAS. RAS GIS Export File


B-8

Additional Cross Section Properties

ial data uective flow a bloc

the Cross Section of inforsection properties is summarized in Table B-4.

Table B-4. Additional cross section pro ata file.


Geospatineff

sed for displayreas, and block

purposes in HEC-RAS for levees, ked obstructions are stored outside of mation. A summary of additional cross

perties options for the spatial d

Levee records

BEGIN LEVEES: None

LEVEE ID: String Levee identifier. Corresponds to ID in LEVEE POSITIONS object on cross section.

SURFACE Lh

END L

Ineffective flow area records

BEGIN INEFFECTIVE None Marks beginning of Ineffective Areas

ID: onds to

N: n

ECTIVE

tion reco

BEGIN BLOCKED None Marks beginning Blocked Obstructions

NS

on.

POLYGON: Location array

Array elements contain 2D coordinates of ineffective area polygon points.

END BLOCKED AREAS: None Marks end of Blocked Obstructions object.

Marks beginning of Levees object.

INE: Location array

Array elements contain 3D coordinates of levee profile points. Array concludes witEND:

EVEES: None Marks end of Levees object.

AREAS: object.

INEFFECTIVE String Ineffective area identifier. CorrespID in INEFFECTIVE POSITIONS object on cross section. Concludes with an “END:”.

POLYGO Locatioarray

Array elements contain 2D coordinates of ineffective area polygon points.

END INEFFAREAS:

None Marks end of Ineffective Areas object.

Blocked obstruc rds

AREAS: object.

BLOCKED ID: String Blocked obstructions identifier. Corresponds to ID in BLOCKED POSITIOobject on cross secti


B-9

Bridge/Culverts

ins with a record containing only RTS:" and ends with a record

containing only the keyword "END BRIDGE/CULVERTS:". A bridge is g

ns ave other optional records. A summary of Bridge/Culvert

cords is provided in Table B-5.

Table B-5. Bridge/Culvert options in the spatial data format file.


The bridge/culvert data section begthe keyword "BEGIN BRIDGE/CULVE

represented by multi-record object beginning with a record containinonly the keyword "BRIDGE/CULVERT:" and ending with a record containing only the keyword "END:."

Bridges/Culverts have the same required records as the Cross Sectioobject, but hre

BRIDGE/CULVERT: None Marks beginning of Bridge/Culvert object.

END: None M t.

The fol requi

STREAM ID: String Identi ch the bridge/culvert resides.

REACH ID: String Identifier for the Reach on which the br

STATION: Float R the bridge on the river reach.

CUT LINE: Location array

Aof ocation.

Sarray

f bridge deck.

T records are op but reco

N St D

US DISTANCE: Float Di on.

T Flo To

arks end of a Bridge/Culvert objec

lowing records are red for a Bridge/Culvert object.

fier for the River on whi

idge/culvert resides.

elative position of

rray elements contain planar coordinates bridge l

URFACE LINE: Location Array elements contain 3D coordinates o

he following tional ( mmend) for a Bridge/Culvert object.

ODE NAME: ring escription of cross section.

stance to upstream cross secti

OP WIDTH: at p width of bridge deck.

Inline Structures

The inline structures data section begins with a record containing only the keyword "BEGIN INLINE STRUCTURES:" and ends with a record


B-10

containing only the keyword "END INLINE STRUCTURES:". An inline ture is represe i object beginning with a record

containing only the keyword "INLINE STRUCTURES:" and ending with a

same line Stru Table B-

Table B-6. Inline structure options in the spatial data format file.

Keyword Value Type V

struc nted by mult -record

record containing only the keyword "END:."

Inline structures have the required records as the Bridge/Culvertobject. A summary of 6.

In ctures records is provided in

alue

INLINE STRUCTURES: None Marks beginning of Inline Structure object.

END: No M cture object.

T

S Stri Identi nline st

R St Id inline structure resi

STATION: Float R ure on th

C Loarray

Aof

SUR E: Location arr

Array elin

The following records are optional (but recommend) for an Inline Structure object.

NODE NAME: on of inline structure.

US DISTANCE: Float Distance to upstream cross section.

TOP W

ne arks end of a Inline Stru

he following records are required for a Inline Structure object.

TREAM ID: ng fier for the River on which the iructure resides.

EACH ID: ring entifier for the Reach on which thedes.

elative position of the inline structe river reach.

UT LINE: cation rray elements contain planar coordinates inline structure location.

FACE LINay

ements contain 3D coordinates of line weir profile.

String Descripti

IDTH: Float Top width of inline weir.

Lateral Structures

The lateral structures data section begins with a record containing only the keyword "BEGIN LATERAL STRUCTURES:" and ends with a recorcontaining only the keyword "END INLINE STRUCTURES:". A lateral structure is represented by multi-record object beginning with a recocontaining only the keyword "LATERAL STRUCTURES:" and ending wi

d

rd th

a record containing only the keyword "END:."


B-11

Lateral structures have the same required records as the inline structures object. A summary of Lateral Structures records is provided in Table B-7.

Keyw

Table B-7. Lateral structure options in the spatial data format file.

ord Value Type Value

LATERSTRUC

AL TURES:

None Marks beginning of Lateral Structures object.

END:

The fol

STREA

REACH ateral resides.

STATIO e on

CUT LI

SURFA

The fol

ring Description of lateral structure.

Distance to upstream cross section.

TOP W

None Marks end of Lateral Structures object.

lowing records are required for a Lateral Structure object.

M ID: String Identifier for the River on which the lateral structure resides.

ID: String Identifier for the Reach on which the lstructure

N: Float Relative position of the lateral structurthe river reach.

NE: Location array

Array elements contain planar coordinates of lateral structure location.

CE LINE: Location array

Array elements contain 3D coordinates of weir profile.

lowing records are optional (but recommend) for a Lateral Structure object.

NODE NAME: St

US DISTANCE: Float

IDTH: Float Top width of weir.

EAS:" and ends with a record

Table B-8. Storage area options in the spatial data format file.

Storage Areas

The storage areas data section begins with a record containing only the keyword "BEGIN STORAGE ARcontaining only the keyword "END STORAGE STRUCTURES:". The keyword “SA ID:” identifies a storage area object. A summary of Storage Areas records is provided in Table B-8.


B-12


SA ID: String Storage area identifier.

POLY with an

Volume)

The fol

TERRAIN: Float array X,Y,Z coordinates for terrain data within storage area. Concludes with an “END:”.

GON: Location Array elements contain 2D coordinates of array storage area boundary. Concludes

“END:”

ELEVATION-VOLUME: Float array Elevation volume information for storage area. (Elevation, Concludes with an “END:”

lowing records are optional for a Storage Area object.


The storage area connections data section begins with a record containing only the keyword "BEGIN SA CONNECTIONS:" and ends

n records is provided in Table B-9.

Keywo Type Value

with a record containing only the keyword "END SA CONNECTIONS:". A summary of Storage Area Connectio

Table B-9. Storage area connection options in the spatial data format file.

rd Value

SACON area connection identifier. NID: String Storage

USSA: String Identifier of upstream storage area (SA ID).

SSA: String Identifier of downstream storage area (SID).

D A

Carray

y elements contain planar coordinates of storage area connection location.

SUR

N

TOP WID

UT LINE: Location Arra

FACE LINE: Location array

Array elements contain 3D coordinates of weir profile.

The following records are optional for a Storage Area Connection object.

ODE NAME: String Description of storage area connection.

TH: Float Top width of weir.


B-13

RAS GIS Export File (RASExport.sdf)

ile using the same spatial le. The contents of the file, however,

export file is shown at l elements for data

vided in

C-RAS export options in the spatial data format file

alue Type Value

HEC-RAS exports model results to a text fdata format as the data import fiare not identical. An example HEC-RAS model

ppendix. A summary of modethe end of this aexport from HEC-RAS that differs from the import file is proTable B-10.

Table B-10. HE

Keyword V

The following records are required for Header section of the RAS GIS Export File

NUMBER OF PROFILES: Integer Number of profile exported from HEC-RAS. Required if greater than 1.

PROFILE NAMES: String array Water surface profile names exported from HEC-RAS. Required if number of profiles is greater than 1.

ss Section portion of the Export File

Float array Elevation of water surface at the cross section. The array must contain a value for each profile.

P String array Water surface profile name(s). This must match the name(s) in the Profile Names

f

SURFACE Location ay

A series of 2D locations marking the limits of a water surface on the cross section.

V loat, paired array

Fraction along cut line and value of velocity (fraction, value). Velocity records must follow Profile ID record.

ACTIV ng the limits ce on the cross

section. Used for interpolation of the velocity data.

IC oat, paired array

Fraction along cut line and value of ice thickness (fraction, value). Ice thickness records must follow Profile ID record.

The following records area required in the Cro

WATER ELEVATION:

ROFILE ID:

record.

The ollowing records are optional in the Cross Section portion of the Export File

WATEREXTENTS: arr

ELOCITIES: F

E WS EXTENTS: Location array

A series of 2D locations markiof the active water surfa

E THICKNESS: Fl


B-14


The following records make up a section defining Storage Areas in the Export File

BEGIN STORAGE AREAS: None Marks beginning of Storage Area object.

REAS: None Marks end Storage Area object.

S tring Storage area identifier.

W ation of water surface at the storage array must contain a value for .

P cation ray

Array elements contain 2D coordinates of storage area limits.

T a section defining Bounding Polygons for the water su rt File

B art of boundaries section.

E es section.

P F ct defining the limits ce profile.

Concludes with an “END:”

ing Name of the profile. This must match a name in the Profile Names record in the header.

P n 2D coordinates of e limits. A single profile limit

can be merged from multiple polygons.

END STORAGE A

A ID: S

ATER ELEVATION: Float array Elevarea. The each profile

OLYGON: Loar

he following records main the Expo

ke uprface limits

EGIN BOUNDS: None Marks st

ND BOUNDS: None Marks end of boundari

RO ILE LIMITS: None Marks start of an objeof a single water surfa

PROFILE ID: Str

OLYGON: Location Arrarray

ay elements contaiwater surfac

Water Surface Bounding Polygon

levations at each cross section (one for ram sends a bounding polygon for

e program outputs a new set of ). The bounding polygon

GIS (or CADD) software to face on top of the terrain.

l represent the outer limits of on of the water surface

case, the GIS h cross section the bounding

n data, and

In addition to a water surface e HEC-RAS progeach profile), the

each hydraulic reach in the model (thbounding polygons for each profile computedis used as an additional tool to assist thefigure out the boundary of the water sur

In most cases, the bounding polygon wilthe cross section data, and the actual intersectiwith the terrain will be inside of the polygon. In thissoftwar levations at eace will use the water surface eand create a surface that extends out to the edges ofpolygon. That surface is then intersected with the terrai


B-15

the actual water limits are found as the location where the water depth

ses, the bounding polygon may not represent the oss-section data. For example, if there are levees

which limit the flow of water, then the levees at each cross

doing this, when the information is sent to the GIS, the l prevent the GIS system from allowing water to s of the levees.

ounding polygon is also used at hydraulic dges, culverts, weirs, and spillways. For

the flow is going under a bridge, the bounding bridge opening along the road

n back out to the extent of side. By doing this, the GIS

f the flow through ures are not

Another application of the bounding polygon is in FEMA floodway hen a floodway study is done, the first profile represents

the existing conditions of the floodplain. The second and subsequent by encroaching on the floodplain until some target r surface elevation is met. When the encroached

nt to the GIS, the bounding polygon is set to the limits of r each cross section. This will allow the GIS to

ched water surface (floodway) over the terrain, even does not intersect the ground.

Import/E

cross-section import/export

De• The stream network is represented by a set of interconnected

ne or more connected reaches that mmon Stream ID.

composed of one or more reaches with the same tream ID, and each reach in a stream must have a unique Reach

very reach must be identified by a unique combination of nd reach IDs.

is zero.

However, in somthe cr

e caextents of represented in the HEC-RAS model, the bounding polygon will only extend out tosection. Bybounding polygon wil

eshow up on both sid

In addition to levees, the bstructures such a

e, if all of s bri

examplpolygon is brought into the edges of the embankment on the upstream side, and thethe cross-section data on the downstreamwill be able to show the contraction and expansion othe hyd ulic structraulic structures, even if the hydrageometrically represented in the GIS.

studies. W

profiles are runincrease in wateprofile is sethe encroachment fodisplay the encroathough the water surface

xport Guidelines

The following rules apply to channel anddata.

fining the River Network

reaches. A stream is a set of oshare a co

• A stream is SID. Estream a

• Stre lphanumeric strings. Reach am IDs and Reach IDs are aendpoint IDs are integers.


B-16

• Streams cannot contain parallel flow paths. (If three reaches connect at a node, only two can have the same Stream ID.) This prevents ambiguity in stationing along a stream.

• A reach is represented by an ordered series of 3D coordinates, and ID, a Reach ID, and IDs for its endpoints.

d by its 3D coordinates and y an integer ID.

t can be connected at their ork.

the order of pstream or "from" end of the

reach, the other marks the downstream or "to" end of the reach.

ies of 3D coordinates, and h name (which must refer to

an existing stream and reach) and a station, indicating the distance wnstream end of the stream.

tion line can cross a reach line exactly once, and cannot cross another cross-section line.

ater surface calculation are exported in a file that oss-section locations in plane (2D) coordinates, water-

and boundary polygons for

Water Surface Export Data Rules n is represented by a water surface elevation and a

series of 2D coordinates on the cross-section cut line. The full oss-section is included.

ing polygon is created for each reach in the stream rofile.

ygon is made up of the most upstream e reach, the endpoints of all cross-sections on

d the most upstream cross-sections of reaches of the reach.

, the endpoints of water surface at the dway, a leveed

rolled by a es that are

higher tha CADD or GIS

identified by a Stream

• A reach endpoint is represententified bide

• Reaches are not allowed to cross, buendpoints (junctions) to form a netw

• The reach is indicated by its endpoints. One point marks the u

normal direction of flow on a

Defining Cross Sections • Each cross section is defined by a ser

identified by a stream name and reac

from the cross-section to the do

• A cross-sec

Results of a wns crcontai

surface elevations for the cross-sections,the reaches.

• A cross-sectio

width of the cr

• One boundnetwork, and for each p

• A reach’s bounding polcross-section on ththe reach, andownstream

• For purposes of defining bounding polygons onlya cross-section are adjusted to the edge of the cross-section if the cross-section is part of a floo

e reach, or the water extent is contsection of thhydraulic structure. This allows calculated water surfac

n the land surface to be reported back to the program.


B-17

Sample RAS GIS Import File #This file is generated by HEC-GeoRAS for ArcGIS BEG

DTM TYPE: TIN DTM: C:\Examples\Baxter\baxter_tin STREAM LAYER: C:\Examples\Baxter\baxter.mdb\River NUMBER CROSS-SECTION LAYER: C:\Examples\Baxter\baxter.mdb\XSCutLines NUMBER MAP PROJECTION: STATEPLANE PROJECTDATUM: VERTICABEGIN S XMIN YMIN XMAX YMAXEND SPA

UNITS: FEE BEGIN STREAM NETWORK:

ENDPOINT: 6453740, 2051685, 60, 1

035323, 32.95776, 3 9280, 52.14808, 4

er

, 2051684.77998051, 59.99999997, 89378.4140625 lines omitted --- 48157.06640625

END: REACH:

STREAM ID: Baxter River REA ID: FROM POINT: 2 TO POINT:

1540.44998505, 2051194.18999834, 34.00000001, 48157.06640625 --- many lines omitted ---

57, 2035323.14001705, 32.95775604, 0 D:

ACH: STREAM ID: Tule Creek REACH ID: Tributary FROM POINT: 4 TO POINT: 2 CENTERLINE: 6426446.76000561, 2059279.84000069, 52.14807890, 12551.4970703125

--- many lines omitted ---

IN HEADER:

OF REACHES: 3

OF CROSS-SECTIONS: 173

ION ZONE: NAD83 L DATUM: PATIAL EXTENT: : 6366478.85990533 : 2010839.52690533 : 6468128.45990533 : 2112489.12690533 TIAL EXTENT: TEND HEADER:

ENDPOINT: 6421541, 2051194, 34, 2 ENDPOINT: 6387438, 2ENDPOINT: 6426447, 205

REACH: STREAM ID: Baxter RivREACH ID: Upper ReachFROM POINT: 1 TO POINT: 2 CENTERLINE: 6453739.98997957

any --- m6421540.44998505, 2051194.18999834, 34.00000001,

CH Lower Reach

3 CENTERLINE: 642

6387438.240013EN RE


B-18

6421540.44998505, 2051194.18999834, 34.00000001, 0 END:

BEGIN CROS

CROSS-SSTREAM ID: Baxter River REACH ID: Upper Reach STANODBANREACH LENGTHS: 343.447, 815.2449, 627.6476 NVA

UT INE: 5948

3739816 6449753.01716107, SURFACE LINE: 43617, 2049658.48075948, 125.00000002

many lines omitted --- 10208855, 110.31235503

END: CROSS-SECTION:

STREAM ID: Baxter River REACH ID: Upper Reach STANODBANREACH LENGTHS: 223.1558, 229.2013, 233.3537 NVALUES: LEVINEFFECTIVE POSITIONS: 61, 93.26781 BLOC .CUT LINE: 6446531.40685930, 2048445.67038340 3954 40073 6446140.35770426, 6446028.38145080, 2049909.17358660 6445838.02350501, 2050713.98307530 SUR

38.02350501, 2050713.98307530, 105.40263370 END: --- man

END STREAM NETWORK:

S-SECTIONS:

ECTION:

TION: 84815.69 E NAME: K POSITIONS: 0.5417204, 0.6313727

LUES: 0, 0.06 0.2595427, 0.035 0.6867172, 0.06

LEVEE POSITIONS: INEFFECTIVE POSITIONS: BLOCKED POSITIONS: C L 658.48076451252.61043617, 2049

6450473.97548097, 2050754.32051480.10208855

6451252.610---

6449753.01716107, 2051480.

TION: 77909.16 E NAME: K POSITIONS: 0.4635276, 0.572924

0, 0.06 0.4353712, 0.035 0.6486487, 0.06 EE POSITIONS:

354, 0, 0.36307355, 0.6235623, 1, 105.4026 KED POSITIONS:

37786, 0.9548786, 79.19141 379, 0

6446341.91498890, 2048655.03936446207.54346581, 2049102.944

2049409.01289628

FACE LINE: 6446531.40685930, 2048445.67038340, 93.26781466

--- many lines omitted --- 64458

y Cross Sections omitted ---


B-19

CROSS-S

STREAM ID: Baxter River REASTANODE NAME: BANK POSITIONS: 0.2088515, 0.2746628 REACH LENGTHS: 678.4368, 652.6373, 592.5861 NVALUES: 0, 0.06 0.5760272, LEV INEBLOCUT 6412787.19596798, 2042663.48848210 SUR 5862274

77.57256318 END:

END CROSS- BEGIN BRID

BRIDGE/STRREASTANODUS TOPCUT 594125 2052519 5468559 947382 936919 SUR 594125, 88.73309329

d --- 2.38936919, 83.88871764

END: --- many Bridges/Culverts omitted ---

END BRIDGE BEGIN LEVE

LEVEE ISUR

6416224.46794023, 8201.03890064, 80.30300144 d ---

6408127.91921907, 73.83999635 END:

ECTION:

CH ID: Lower Reach TION: 34251.78

0.2023585, 0.035 0.05

EE POSITIONS: 380, 0.5949767, 72.00802 FFECTIVE POSITIONS: CKED POSITIONS: LINE:

6412627.43755387, 2043633.45026854 6412056.87180271, 2047399.18430193 FACE LINE: 6412787.19596798, 2042663.48848210, 80.1

--- many lines omitted --- 399.18430193,6412056.87180271, 2047

SECTIONS:

GES/CULVERTS:

CULVERT: EAM ID: Tule Creek CH ID: Tributary TION: 4514.028 E NAME: Yosemite Street DISTANCE: 100 WIDTH: 96 LINE: 6422221.24109452, 2055203.79

127.26421766.89378999, 20556421302.33643314, 2054958.76421128.76554372, 2054912.806420924.56454467, 2054892.38FACE LINE: 6422221.24109452, 2055203.79

--- many lines omitte6420924.56454467, 205489

S/CULVERTS:

ES:

D: 380 FACE LINE:

204--- many lines omitte

2047348.05802148,


B-20

END LEVEES BEGIN INEF

INEFFECPOL

END:

INEFFEC

POL 188569 118551

d --- 188569

END:

--- many Ineffective Areas omitted --- END INEFFE

BEGIN BLOC BLOCKED

POL 567028 750541 491178 567028

END: END BLOCKE

BEGIN LATE

LATERAL

303

97, 2047168.40301990, 69.83999637

6402363.56369299, 2045153.60574580, 65.27986148 END:

END LATERAL STRUCTURES:

:

FECTIVE AREAS:

TIVE ID: 354 YGON: 6446126.65267778, 2049275.06766575 6446347.63945516, 2049062.58037434 6446466.63230616, 2048960.58649530

d --- --- many lines omitte6446126.65267778, 2049275.06766575

TIVE ID: 355 YGON: 6446009.40721919, 2049877.886445816.78229256, 2050758.82

--- many lines omitte6446009.40721919, 2049877.88

CTIVE AREAS:

KED OBSTRUCTIONS:

ID: 379 YGON: 6422107.09773554, 2052558.246423542.24950153, 2052503.046422076.43212521, 2052184.126422107.09773554, 2052558.24

D OBSTRUCTIONS:

RAL STRUCTURES:

STRUCTURE: STREAM ID: Baxter River REACH ID: Lower Reach STATION: 27469.68 NODE NAME: North LS US DISTANCE: 0 TOP WIDTH: 20 CUT LINE: 6407389.53497197, 2047168.40301990 6406371.11447597, 2046886.24321

--- many lines omitted --- 402363.56369299, 2045153.60574580 6

SURFACE LINE: 6407389.534971

--- many lines omitted ---


B-21

BEGIN S

s omitted --- 30.51958869

8.34, 2.241535E+07 53E+07

70.84, 4.921408E+07

.095226E+07

9E+08

END STO BEGIN S SA SACONN ID: 444 TOP WIDTH: 20

NE: 7, 2047168.40301990 7, 2046886.24321303 lines omitted ---

0574580

0301990, 69.83999637

0574580, 65.27986148 END END SA

TORAGE AREAS: SA ID: 369

POLYGON: 6402631.96981374, 2045430.51958869 --- many line 6402631.96981374, 20454END: ELEVATION-VOLUME: 63.34, 0 64.59, 272682.8 65.84, 2102153

7.09, 1.130536E+07 66

69.59, 3.5058 72.09, 6.477892E+07 73.34, 8

74.59, 9.734569E+07 75.84, 1.14224END: TERRAIN: END: RAGE AREAS:

A CONNECTIONS:

CONNECTION:

NODE NAME: US SA: 369 DS SA: 371

CUT LI 6407389.5349719 6406371.1144759

--- many 6402363.56369299, 2045153.6 SURFACE LINE: 6407389.53497197, 2047168.4

--- many lines omitted ---6402363.56369299, 2045153.6

:

CONNECTIONS:


B-22

Sample RA1Feb2005 16:18

ADER:

IN DTM: C:\Examples\Baxter\baxter_tin STREAM LAYER: C:\Examples\Baxter\baxter.mdb\River

MAP PROJECTION: STATEPLANE PROJECTION ZONE: DATUM: NAD83 VERTICAL DATUM: BEGIN SPATIALEXTENT:

XMIN: 6366478.85990533 YMIN: 2010839.52690533 XMAX: 6468128.45990533 YMAX: 2112489.12690533

END SPATIALEXTENT: NUMBER OF PROFILES: 3 PROFILE NAMES: 50yr 100yr 500yr NUMBER OF REACHES: 3 NUMBER OF CROSS-SECTIONS: 179 END HEADER: BEGINSTREAMNETWORK: ENDPOINT:6421540.50,2051194.25, , 1 ENDPOINT:6453739.99,2051684.78, , 2 ENDPOINT:6387438.24,2035323.14, , 3 ENDPOINT:6426446.76,2059279.84, , 4 REACH: STREAM ID: Baxter River REACH ID: Upper Reach FROM POINT: 2 TO POINT: 1 CENTERLINE: 6453739.99, 2051684.78, ,

6421540.45, 2051194.19, , END: REACH: STREAM ID: Baxter River REACH ID: Lower Reach FROM POINT: 1 TO POINT: 3 CENTERLINE: 6421540.45, 2051194.19, ,

6387438.24, 2035323.14, , END: REACH: STREAM ID: Tule Creek REACH ID: Tributary

S GIS Export File # RAS export file created on Mon 2# by HEC-RAS Version 3.1.3 BEGIN HE UNITS: DTM TYPE: T CROSS-SECTION LAYER: C:\Examples\Baxter\baxter.mdb\XSCutLines


B-23

FROM POINT: 4

6421540.45, 2051194.19, ,

BEGIN CROSS-SECTIONS:

WATER SURFACE EXTENTS: 6450877.21, 2050186.83, 6450289.15, 2050940.40 6450896.85, 2050159.18, 6450262.99, 2050966.73 6450912.28, 2050137.47, 6450189.98, 2051040.23 PROFILE ID:50yr

0.64436, 1.926

2.972 3.829

0.55086, 5.019 .459

0.58709, 7.245 6.737

PROFILE ID:500yr

0.66467, 4.272 SURFACE LINE: 6451252.61, 2049658.48, 125.00 --- many lines omitted ---

TO POINT: 1 CENTERLINE: 6426446.76, 2059279.84, ,

END: ENDSTREAMNETWORK:

CROSS-SECTION: STREAM ID:Baxter River REACH ID:Upper Reach STATION:84815.69 NODE NAME: CUT LINE: 6451252.6104362 , 2049658.4807595 6450473.975481 , 2050754.3373982 6449753.0171611 , 2051480.1020886 REACH LENGTHS:826.24,806.49,525.17 BANK POSITIONS:0.45159,0.51309 LEVEE POSITIONS: 380,0.93260,79.95625 WATER ELEVATION:70.39427,76.72782,86.74971

VELOCITIES: 0.32733, 1.558 0.46174, 2.381 0.55094, 3.764 0.56925, 4.280 0.58721, 6.164 0.60317, 5.713 0.62166, 3.942

PROFILE ID:100yr VELOCITIES: 0.31866, 0.45698,

0.56908, 5

0.60341, 0.62189, 5.168 0.65404, 3.202 VELOCITIES: 0.31332, 4.739 0.45464, 5.533 0.55081, 6.526 0.56894, 6.860 0.58698, 8.456 0.60365, 7.890 0.62206, 6.635


B-24

4 END:

49753.02, 2051480.10, 110.31

CROSS-SECTION:

67044,69.44948,78.49661 WATER SURFACE EXTENTS: 6421432.49, 2052554.70, 6420609.83, 2052432.00

791.77, 6420316.40, 2052634.53

VELOCITIES:

0.77035, 0.444 0.77857, 0.350 0.81222, 0.177

VELOCITIES:

0.407 0.76221, 0.444

6422369.20, 2052943.66, 80.22

STREAM ID:Tule Creek REACH ID:Tributary STATION:1595.102 NODE NAME: CUT LINE: 6422369.1971783 , 2052943.6596315 6421588.0439919 , 2052573.50648 --- many lines omitted --- 6420275.0509832 , 2052670.3666247 WATER ELEVATION:62.

6421570.89, 2052571.43, 6420459.69, 2052510.35 6422048.65, 2052 PROFILE ID:50yr VELOCITIES: 0.47364, 0.016 0.65126, 0.056 0.74604, 0.171 0.75411, 0.221 0.76221, 0.247 0.77030, 0.207 0.77842, 0.151 0.79265, 0.059 PROFILE ID:100yr

0.44844, 0.116 0.62783, 0.185 0.74591, 0.383 0.75406, 0.466 0.76221, 0.514

0.86985, 0.096 PROFILE ID:500yr

0.21051, 0.019 0.42227, 0.092 0.62301, 0.192 0.74582, 0.350 0.75403,

0.77039, 0.393 0.77866, 0.327 0.81602, 0.232 0.88706, 0.146 0.94874, 0.075 SURFACE LINE:

--- many lines omitted --- 6420275.05, 2052670.37, 85.26

END: END CROSS-SECTIONS:


B-25

BEGIN STORAGE AREAS: SA ID: 369 WATER ELEVATION:65,65,65 POLYGON: 6402631.9698137 , 2045430.5195887 , 6402648.7543614 , 2046009.5857725 , --- many lines omitted --- 6402631.9698137 , 2045430.5195887 , END: SA ID: 370 WATER ELEVATION:65,65,65

584.9518455 ,

PROFILE ID:100yr

6420143.38,2052744.69,69.17 END:

POLYGON: 6449753.02,2051480.10,86.75 --- many lines omitted --- 6449462.09,2051308.23,86.83

POLYGON: 6411089.902679 , 2043 6411100.24735 , 2041762.9675571 , --- many lines omitted --- 6411089.902679 , 2043584.9518455 , END: END STORAGE AREAS: BEGIN BOUNDS:

PROFILE LIMITS: PROFILE ID:50yr POLYGON: 6449753.02,2051480.10,70.39 --- many lines omitted --- 6449462.09,2051308.23,70.35 POLYGON: 6424775.60,2059535.58,62.69 --- many lines omitted --- 6424246.32,2059434.43,62.69 POLYGON: 6420221.24,2052718.80,62.36 --- many lines omitted --- 6420143.38,2052744.69,62.32 END: PROFILE LIMITS:

POLYGON: 6449753.02,2051480.10,76.73 --- many lines omitted --- 6449462.09,2051308.23,76.73 POLYGON: 6424775.60,2059535.58,69.51 --- many lines omitted --- 6424246.32,2059434.43,69.52 POLYGON: 6420221.24,2052718.80,69.19 --- many lines omitted ---

PROFILE LIMITS: PROFILE ID:500yr


B-26

POLYGON: 6424775.60,2059535.58,78.54

--- omitted -

POLYGON: 64202 2718.80, --- many lines omitted --- 6 .6 END: END BOUNDS:

6424246.32,2059434.43,78.54

many lines --

21.24,205 78.18

420143.38,2052744 9,78.16

Appendix C HEC-RAS Results Interpolation

C-1

A P P E N D I X C

EC-RAS results may be interpolated spatially between cross section so

stream n

delineation; therefore, interpolation must be done using preexisting EC-RAS output (RASEXport.sdf).

in detail; interpolation of Shear

meters

Software

-GeoRAS software is comprised of several DLLs and one executable to access the

registered with the operating system; however, you must have the .NET

y

boundaries to the specified format.

HEC-RAS Results Interpolation

H

ai

locations within HEC-GeoRAS, but the interpolation program can albe used as a “stand-alone” piece of software. The interpolation process allows for interpolation of velocity, shear stress, power, and ice results subsequent to performing the floodpl

floodplain boundary results and the HInterpolation of Velocity is discussedStress, Stream Power, and Ice Thickness data may be accomplished using identical methods (specifying the “shear”, “power”, “ice” keywords rather than the “velocity” keywords in the paraimport file). Results may be viewed in ArcGIS.

The interpolation of data outside of the HEC

interpolation routines. It is not required that the software is

Framework 2.0 installed on the computer. The interpolation software components are enumerated below.

1. XSTransitionEXE.exe

2. XSTransition.dll

3. MatrixSolutions.dll

4. HECGraphics.dll

It is suggested the software is copied to the same directory in which the required data are stored, for user simplicity, but it is not necessar(by default this software is installed to the “C:\Program Files\HEC\HEC-GeoRAS\bin” directory).

Additionally, the VBA script (“Export_Flood2XML”) may be needed to export floodplain


C-2

Required D

results (with velocity, shear stress, stream power, ice, etc) including bank station data, floodplain

new output parameter specifying the water surface extents of the

ty

s S

he

The floodplain boundaries for each profile must be exported to the y be contained in a separate file

(referred to as the Floodplains file) or the data may be appended to

ed to export floodplain expects the profile as generated using HEC-

g the floodplain boundaries are

” root node. All “FloodplainBoundaries” uded in the RAS Export

attribute identifying the n

ata

There are three pieces of required data for use with the interpolation software: the HEC-RAS exported

boundaries for each water surface profile, and input parameters identifying what to process. [The final release of HEC-RAS 4.0 has a

active conveyance area (Active WS Extents) important to the velociinterpolation routines.]

HEC-RAS Export File

The HEC-RAS export file must be in the form of the RASExport.xml file. This file is generated by taking the RASExport.sdf file and processing it using the SDF2XML converter program installed with HEC-GeoRAS (the SDF2XML program may also be executed separately from GeoRAS). Conversion from the SDF format to the XML format ithe first step when performing inundation mapping using HEC-GeoRA– it is assumed that the inundation mapping will be performed to develop the floodplain boundaries.

The HEC-RAS results GIS file is referred to as the RAS Export file. TRAS Export file must contain simulation results for the data to be interpolated; therefore, the user must turn on the correct simulation options in HEC-RAS and choose to export the data to the GIS export file.

Floodplain Boundaries

specified XML format. The data ma

the RAS Export file.

The VBA script “Export_Flood2XML” may be uslayers from ArcMap to an XML file. The scriptnames to be of the form “bP00n” or “b P00n” GeoRAS. Directions for exportinprovided in this step-by-step example.

The Floodplains.xml file must have a “RAS2GISfloodplain boundaries are contained within thenode (in order that the boundaries may be inclfile) and each floodplain boundary described by the “FloodplainBoundary” node with the “ProfileID”profile name. The structure of the Floodplains.xml file is shown iFigure C- 1.


C-3

ing the . This file is

e RAS Export es the

ed from the

are shown in Figure C- 2.

Figure C- 1. Floodplains.xml structure for the floodplain boundary node.

Interpolation Parameters

The interpolation Parameters.xml file is used for establishprofiles to process and RAS results parameters of interestalso used to establish the file names and locations for thfile and the Floodplains.xml file. Lastly, this file establishregistration information for the resulting grids comput

terpolation. An example of the parameters used for velocity analysis in

Raster parameters may be created by looking at depth grid source

r ent in the parameters file, the output grids will be

“tiled” based on the raster parameter values in a directory based on the ProfileID value.

Figure C- 2. The Parameters.xml file establishes what will be processed.

data developed by HEC-GeoRAS through the ArcMap interface. (The ESRI GRID format uses -9999 for ‘No Data’ cells.) If multiple Rastenodes are pres

Individual parameter values for velocity, shear stress, stream power, and ice thickness are provided in Table C- 1.


C-4

Table C- 1. Parameter file keywords for HEC-RAS results interpolation.

me Parameter Values Value GridParameter Na Abr

Velocity Velocities VelocityValues Velocity vel

Ice Thickness eThickness ice IceThicknessData IceThicknessValues Ic

Shear Stress ShearStressData ShearStressValues ShearStress shear

Stream Power StreamPowerData StreamPowerValues StreamPower power

Example

This example guides you through how to do interpolation of velocity data outside of HEC-GeoRAS using the “Example Data” provided with the stand-alone version of the interpolation software.

Establish Workspace

Create a directory for the interpolation software.

You will also need the geodatabase of floodplain boundaries from“data” directory (or you can use your own shapefiles or geodatabase)and a corresponding RASE

the

xport.sdf file.

EC-GeoRAS toolbar (Version 4.2) or the stand-alone

Convert RAS Export file to XML

Convert the RASExport.sdf file to the XML equivalent. This is done using the HSDF2XML.exe program.


C-5

Open a New ArcMap Document

Create a new ArcMap document and save it to the workspace location.

Load the Floodplain Boundary Layers

Load the floodplain boundaries into the ArcMap document.

to the output geodatabase using the same name structure.

The floodplain boundary names should be of the generic form of the ProfileID - “bP00n” or “b P00n”. The parameter data is stored in the RAS Export file based on the ProfileID and the floodplain boundary feature classes are written


C-6

Export Floodplains to XML

e data. ed data will be created in the location of the MXD

with the name “Floodplains.xml”.

You must load the “Export_Flood2XML” VBA script to export thBy default the export

You first need to create a new button to attach the script to. Click on the Tools | Customize menu item. Click on the Commands tab.

ol

then click Create.

Choose to “Save in” the active project if you don’t want to see the toin future ArcMap documents.

Click the New UIControl button.

Select the UIButtonControl (default) and

s is shown below).

This adds a new Command in the Commands list. Select it and rename it to something meaningful to you (Project.ExportFloodplain


C-7

Next, drag the new button up onto a toolbar. Here it is added to the GeoRAS toolbar.

age menu it other

Right-click on the tool and choose the Change Button Imem and select an image so you can pick it out from all your

custom tools.


C-8

Right-click on the button and choose the View Source menu item (at the bottom). This opens the VBA editor. Now copy and paste the

the text file into the code window beneath the Click event for the button you just created.

ort_Flood2XML”.

Export_Flood2XML subroutine from

Next, type in (or copy and paste) in the Click event for the button thename of the subroutine “Exp

w run the code by ile it is running you tle.

Click back on the ArcMap document. You can noclicking on the new button previously created. Whwill see “[running]” appended to the VBA project ti

When the process finishes, a message box will come up. Note tno error trapping in this piece of code, so check the Floodplains.xmlfile to see if it looks correct. There will be a “FloodplainBoundnode in the XML tree with a ProfileID of the form “P00n”. Eachfloodplain boundary node will have several polygon nodes the floodplain boundary.

here is

ary”

describing

The Floodplains.xml file should have been created in the workspace directory.


C-9

Complete Interpolation Parameters File

The interpolation Parameters.xml file holds the “registration” information for the grids that are going to be created. This indicates

the grid-cell size (number of rows and columns) for the rasterization and the origin of the lower-left corner of the grid. You also specify which profiles you want interpolation to work on and whether to do the velocity, shear stress, stream power, or ice thickness information.

To identify the grid file information, load a grid to ArcMap. Right-click on the grid layer name and select the properties menu item. Next, select the Source tab. You can identify the grid-cell size and the Left and Bottom coordinates for the grid. In general, you should choose either the grid with the maximum inundation extent or the terrain grid that was used to perform the floodplain delineation (to be on the safe side, use the terrain grid).

u Edit the example “Parameters.xml” file that has been provided to yofor your specific dataset.


C-10

Multiple Profiles

Specify multiple profiles in the one Parameters.xml using the “Transitions” node.

An alternate option is to create a new Parameters.xml file for each profile. You can duplicate the parameters file and then edit the profile number. Next, you will have to run each of the parameter files one after another. A batch file is handy for this.

Running the Interpolation

There are several ways to run the interpolator. The easiest is to edit the included batch file (Interpolate.bat) with the path name to parameters file. (Note that the bat file calls XSTransistionsEXE program and passes the Parameters.xml filename all on the same line.) The Interpolate.bat file is at the location of the sample data. The “pause” in the batch file will inform you when the process is complete by taking you to a command prompt (hit the space bar to continue). More importantly, the “pause” allows you to see if the process didn’t run due to a bad file name!

- or –

If the data is in the same location as the interpolator, you can just drag the Parameters.xml file onto the XSTransitionEXE.exe file.


C-11

- or –

From the command line type something like the following: "C:\Examples\Velocity Interpolation\Software\XSTransitionEXE” "C:\Examples\Velocity Interpolation\Data\parameters.xml"

While the interpolation is processing a dialog will appear showing you the status of the computations.

When the interpolator has finished, it will have created a binary file (or files) in the ESRI Binary Floating Point format. This format is fairly efficient and can be easily transferred. The file will have the “.flt” extension.

If raster tiling is indicated in the Parameters.xml file (because there are multiple Raster nodes) the computed grids are stored by ProfileID and then broken up by the Raster (tile) name. Because ESRI grids names must be 13 characters or less, the combination of the GridAbr and Raster Name (or ProfileID) must be 13 characters or less.


C-12

229BImport to ESRI GRID (Single Grid)

After the FLT files are created, open ArcToolbox and import the data to an ESRI grid. Navigate the ArcToolbox to Conversion Tools | To Raster | Float to Raster.

Open the tool and specify the input and output grid name.

The grid will not have the projection information. However, you can define the projection, or just copy and paste the “prj.adf” file from the depth or terrain grid used for the raster registration in the parameters file.

230BImport to ESRI GRID (Multiple Grids)

You can do this a couple different ways from ArcCatalog using a script or from the Command Line.

Open ArcCatalog.


C-13

To use the script method, select the Tools | Macros | Visual Basic Editor menu item. In the Project Pane, navigate to Normal | ArcCatolog Objects | ThisDocument.

Copy and paste the script provided in the “Float2Grid.txt” file. Change the directory paths making sure the pathnames are valid and the output directory exists!

Verify that you have the “Microsoft Scripting Runtime” reference option turned on using the Tools | References menu option.

Run the script.

If you would rather use the command line, select the Windows | Command Line menu item. Create multiple entrees in a text


C-14

document that specify the command followed by the .flt file and the output locations. For instance:

FloatToRaster_conversion “C:\Data\velP001.flt” “C:\Data\Vel_Grids\velP001” FloatToRaster_conversion “C:\Data\velP002.flt” “C:\Data\Vel_Grids\velP002” FloatToRaster_conversion “C:\Data\velP003.flt” “C:\Data\Vel_Grids\velP003”

Copy and paste the items in the Command Line and press Return. The files will be converted to ESRI grid format as specified.

Regardless of the method used, the grid(s) will not have the projection information. You can define the projection using the ArcGIS tools, or just copy and paste the “prj.adf” file from the depth or terrain grid used for the raster registration in the parameters file.

Documents

HEC-GeoRAS Users Manual